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Furnace troubleshooting questions with answers index

Below we have quick links to pages where problems and solutions are discussed for your quick reference and hopefully a quick solution to your problem. Special thanks are in order for the many people who took the time to make the YouTube videos that are included on our pages! I know that it is much easier for me to learn if I can see the problem and repair through a video or picture! Near the bottom of each page there is an area that allows you to comment or ask questions. If you have any questions please send us an email anytime: or comment on the perspective page. We would love to help you out, answer your questions and earn your business! Hope you have a blessed day! Steve & Barbara Arnold

One of my favorite quotes by David Jeremiah: “Nothing is more valuable than helping another person succeed!”

  1. Problem: Furnace blink code shows I have a pressure switch problem. Replaced pressure switch. Still have a problem?
  2. Problem: Will the pressure switch correct my water drainage problem? (With two YouTube Videos)
  3. Problem: Why does my furnace rollout switch have to be reset so often? Why do rollouts have different temperature differences? (With two YouTube Videos)
  4. Problem: Why does my furnace air conditioner have poor air flow? (With one YouTube Video)
  5. Problem: How do I test and troubleshoot my gas furnace pressure switch? (With one YouTube Video)
  6. Problem: What is the sequence of operation of my 80% gas furnace? (With one YouTube Video)
  7. Problem: Furnace will not ignite. Ignitor will not glow. (With two YouTube Videos)
  8. Problem: Furnace or water heater pilot will not stay lit. (With one YouTube Video)
  9. Gas & Electric Furnace Troubleshooting Simplified (With one YouTube Video)
  10. Furnace Troubleshooting Flow Chart.
  11. Problem: Furnace comes on, doesn’t run long then shuts off. Will work if thermostat is turned way up. (With one YouTube Video)
  12. Furnace Hot Surface Ignitor Troubleshooting Videos.
  13. Problem: How do I wire up my new thermostat? What do the wire colors mean? (With two YouTube Videos)
  14. Thermostat Replacement (Video)
  15. Furnace Control Board (Video)
  16. Problem: My furnace blower motor will not come on. What could cause the blower motor to not come on? (With one YouTube Video)
  17. Problem: My furnace fan motor will not shut off. Why does the fan run continuously? (With one YouTube Video)
  18. Furnace Blower Replacement (Video)
  19. Problem: Burners ignite the gas valve cuts off after only a second because the pressure switch is opening for a split second.
  20. Problem: Furnace main burner ignites, the main burner stays on for 8 to 10 seconds, then shuts right back off (With one YouTube Video)
  21. Problem: I purchased a flame sensor from you for my Goodman furnace. The new flame sensor did not fix the problem? (With two YouTube Videos)
  22. Problem: Blower shuts off too soon, cycles off and comes back on within 30 seconds
  23. Problem: The fan on your furnace runs all the time and will not shut off (With one YouTube Video)
  24. Problem: Fan will not come on in the “ON” position or your fan will not come on when you turn the thermostat down
  25. Problem: Furnace, air conditioner heat pump will not come on. Blown fuse on board. (With one YouTube Video)
  26. Problem: Draft inducer will not start, ignitor will not glow or gas valve will not open.
  27. Problem: Electric heat will not come on, the fan will not come on. (With two YouTube Videos)
  28. Problem: Why do I have to replace my furnace ignitor every two weeks?
  29. Problem: My Trane IGN00145 Ignitor is going out too often? What could be the problem?
  30. Problem: I have a bad igniter is there any way to light a gas furnace manually?
  31. Problem: How do I troubleshoot my spark ignition gas furnace? (With two YouTube Videos)
  32. Problem: No gas.. bad control board? Frazier Johnson heater.
  33. Problem: My furnace is making a howling noise only in the winter time?
  34. Problem: Why is my heating bill so high? Over $500!
  35. Problem: Could a weak thermostat battery destroy my home?
  36. Problem: Furnace blower motor works intermittently?
  37. Problem: The heater comes on, the gas lights, the furnace warms up, the blower starts then abruptly the gas cuts off.
  38. Problem: The fuse on my control board blows constantly. How do I find where the short is?
  39. Problem: How do I troubleshoot my Honeywell Smart Valve Gas Valve? (With one YouTube Video)
  40. How do I adjust the gas pressure on my natural gas furnace? (With one YouTube Video)
  41. Problem: How do I remove my furnace control board without breaking the plastic pins that hold the board in place? (With one YouTube Video)

72 thoughts on “Furnace troubleshooting questions with answers index

  1. We are looking for someone to help explain how our Losch boiler/furnace. We just moved into this home.It runs on coal. Very old furnace.
    My husband needs help understanding this furnace.

    Any help would be greatly appreciated.

    Thank you.


    1. Hi Mel! I am very sorry, but I do not know anything about coal-fired boiler furnaces. I am that someone will see this post and offer to help you out. I found this website that I hope will help you out: Sorry that I can not give you any advice or help. Steve

    2. My electric furnace runs its cycle but when it turns off it flips the breaker. New filter no restrictions in the duck work. What is the next step. Can you tell me please.

      1. Hi Melody! I would like to suggest that you have an electrician check your electrical circuit for the electric furnace. You might have a loose burnt connection or a breaker that is going bad. Electricity is too dangerous to work on unless you have the proper tools and training. Sorry that I can not be of any help. Steve

  2. I have been reading all of the questions and your reply. I am so thankful that I found your company. My furnace is only 2 years old and in excellent condition. Flame comes on goes out. Sometimes it works for a few days and then it’s out again. I turn the furnace off and on and it strarts back sometimes.. Furnace companies kept telling me my problem was _____________..
    1. your furnace is to big for your house and its over heating. You have an improper install. This company came out and never looked at the sensor. My home warranty people sent him.
    2. your board is bad Advice
    3. a bird could be stuck in the flute.. WHAT!!!
    4. you don’t have enough ducts in your house. Same person as #1
    5. Company that did the install said they would be out to run a diagnostic check on Friday Feb 8 for $243. He never showed up or called.

    Well my friend sent his brother over here today who is an HVAC engineer and he said your flame sensor is dirty. THANK YOU!!! He didn’t have any sandpaper to clean it so he used a cloth. He said best bet is to just order a new one and he will put it in. So far it’s working perfectly. No charge for anything. Just ordered the sensor from your company. Thank you for posting all of this info because I would never have known. Men just don’t want to listen to females. LOL NOTE: I have only been trying to get someone to listen to me since Jan 11…..

    Thank you Donna

    1. Hi Donna! Fantastic! So glad to hear that you found an inexpensive solution to your problem! Thanks so much for your business and for taking the time to post what happened to you! Hope this will prevent other people from having the same problem. God bless you and your family today and always! Steve

  3. I have a Nordyne M1GB 077A BW propane furnace. Pilot is on and steady and blower fan works fine when thermostat is set as Fan On. When the thermostat is set to Heat Auto, the inducer motor hums but that’s as far as it goes. I called a service tech and he diagnosed the inducer motor as the culprit. He also removed the 2 wires from the pressure switch and hotwired them together and told us to run the furnace as needed by turning the furnace power switch on and off. I replaced the inducer motor and no change. I replaced the pressure switch and still no change. And yes, I hooked the wires back to the pressure switch.

    1. Hi Tom! If the inducer will not come on then you either are not getting 24 volts AC from the thermostat between the W and C connections which would be a thermostat or thermostat wiring problem or you are not getting 120 volts AC to the draft inducer to make the draft inducer start which could be a control board problem. I would suggest that you check with a volt meter to make sure that you are getting 24 volts between W and C when the thermostat calls for heating and 120 volts AC to the draft inducer out of the control board to the draft inducer when the thermostat calls for heat. This would determine if you have a thermostat or control board problem. If the draft inducer is getting 120 volts and not turning on then you need a new draft inducer again. I hope you can find and fix the problem. Steve

      1. Correction. After replacing the pressure switch, the inducer motor kicks on but that seems to be all the furnace is willing to do. Thank you for your reply!

      2. Hi Tom! If the ignitor will not glow after the draft inducer comes on then I would suggest that you use a voltmeter to test and see if all your safety controls are closed. Safety controls are the limit, pressure switch and rollout switches. If any of the safety controls are open then current can not flow through them and the control board will not allow the ignitor to glow. If all your safety controls are closed then you might have a control board problem or an ignitor problem. You can test the ignitor to make sure it is not burnt out. I would suggest that you check and make sure all your furnace wire connections are good and tight. We have lots of furnace troubleshooting advice on the following page: I would suggest going through the troubleshooting flow chart to see what is wrong: We also have lots of troubleshooting questions and answers on the following page: If you have any specific questions please let me know. Thanks! I hope you can easily find and fix the problem. Steve

  4. i’ve gone thru 3 thermostats over the last 6 months. the temperature goes haywire and cannot figure out what to do?

    1. Hi Kevin! I am sorry that I really do not know what your problem could be, but I would suggest that you check between the R and C (com) connections on your control board or transformer and make sure you are getting a minimum of 24 volts to the thermostat. Low voltage below 24 volts can mess up a thermostat or any low voltage controls. If you have a humidifier or some other device that is power by 24 volts off your furnace, then this device can cause too much amp draw and cause the thermostat to not be right. Please make sure that all wire connections both at the thermostat and furnace are good and tight. Any loose connections can cause high amp draws and mess up the thermostat’s heat anticipation. I hope you can find and fix the problem soon! Steve

  5. Had a Trane S9V furnace installed last winter. Two days after I noticed my 3 bedrooms and bath were cooler then the kitchen,dining and living rooms. Upon taking temperature readings emanating from the registers the latter were reading 101-102o while the former were reading 80-82o. I checked the ductwork coming off the furnace by feeling it and the backside ducts were hot while the frontside of ducts were cool. Called the installation company and they did nothing to correct the problem saying furnace is operating normally. I don’t think something that’s putting out 20o’s less heat out of one side of furnace can be considered normal. Had another Trane dealer here yesterday and he said it’s the a/c coil but I’m a little leery about that diagnosis since the section below the coil and furnace is hot on backside and cool on frontside. Have you any idea what could be the problem and a fix. I asked the guy yesterday about how to get a Trane field tech to come check what’s going on and he said you will have to have original installer come with the field tech. No way that’s happening.

    1. Hi Carl! I really do not have many ideas on what might be happening other than maybe one of the dampers in your main trunk line ductwork might be partially closed or the installer forgot to take some of the packings off the AC evaporator coil and the coil is partially stopped up. Paper or plastic could have blown up into the underside of the coil and it could be blocking air flow. I would suggest having the bottom of the AC coil checked to make sure there are not any obstructions. Also, check your ductwork to make sure all dampers (if equipped) are open both in the main trunk line and individual supply lines. I hope you can find and fix the problem soon! Steve

  6. Hi Steve, looking for what I think are parts that can solve my issue. I have an Amana furnace, Model DMS90453BXA. We are having trouble getting it to kick on. For context, it can be about 60 degrees in the house. When we set the thermostat to 65 or so, a few things happen. There is a clicking noise and then we hear what appears to be the blower or fan starting. Through the small window in the furnace door, we can see the igniter start to glow a very bright orange, however the burners do not ignite. Instead after a few seconds, the glowing stops and nothing happens, the blower or fan also stops. Then we hear a clicking noise and that process repeats itself three times before stopping all together. At this point, the LED light at the bottom of the furnace, which was a solid red, is now flashing consistently every three seconds. From looking online, it seems like this could be a part problem that might be able to be fixed in a DIY fashion. Thanks for any insight you can provide.

    1. Hi Clay! Since your gas valve is not opening to let gas in to ignite the burners I would think that you might have a safety control open like a pressure switch, limit switch or rollout switch open. You will need a volt meter to do this testing of components. Although most of the time if one of the safeties (pressure switch, limit or rollouts) are open the control board will not allow the ignitor to glow. So more than likely you either have a bad gas valve relay on the control board or a bad gas valve. It would not hurt to test with a meter to make sure all the safety controls are closed before you test the control board or gas valve. I would suggest that you check and see if the gas valve is getting 24 volts to open from the control board when the gas valve is supposed to be opening. If the valve is not getting 24 volts from the control board then I would think you need a new control board. If you are getting 24 volts to the gas valve and the valve is not opening then you need a new gas valve. I hope you can easily find and fix the problem. Steve

  7. steve
    I have Armstrong furnace ser. #8498m15929 every now and then I have to go to furnace and shut it off at the switch and turn back on to get the furnace to ignite other wise it blows cold air do you have parts
    thanks tim wiegand

    1. Hi! Sorry, I do not have an Armstrong furnace parts program where I can look up parts. On most furnaces, if the furnace goes off on limit the fan will continue to run and blow cold air. You might want to check to see if the furnace is going off on high limit which means the furnace has overheated. Some things that would cause a furnace to overheat would be an airflow problem like a dirty filter, dirty AC evaporator coil, a slow blower motor (might need a new motor capacitor) or an obstruction in your return. Many times furnaces will lock out after 3 tries without ignition, but usually, they do not have the blower continue to run. Most furnace lockouts are caused by failure to ignite the burner (possible flame sensor problem) or pressure switch problems where the pressure switch will not open or close. You will need to troubleshoot with a voltmeter the next time the problem occurs. I hope you can easily find and fix the problem. Steve

  8. Steve,
    I have a Payne Furnace Model PG9MAA061OOADKA – Ser. # 5001A10950
    The year before last year I was getting a code 33 (overheating ) the code would go away if I pulled out the Aprilaire 401 filter out. A service tech came out and since I variable speed blower motor he changed it from the factory setting to the highest setting and the problem went away. Last year I purchased a new blower motor and capacitor from you. About a month later the code 33 came back. Now I am back to the furnace will only run with out the filter, if I put the filter in I get the code 33. Any thoughts?

    1. Hi David! Thank you so very much for your business! Sounds like you have an airflow problem or too much gas input which is causing the furnace to over-heat. I would suggest making sure the blower motor’s capacitor is in good condition. This will make the blower slow down if the capacitor is weak. You might try a higher blower speed in the heating mode. I would suggest making sure the evaporator coil is clean on the underside of the coil, and make sure all return ducts are open and not restricted by furniture or other restrictions. Make sure all supply registers are open. You might want to have the gas pressure turned down a little so your furnace does not produce too much heat. I hope you can easily find and fix the problem. Steve

  9. Hi, After we had a thunderstorm our air conditioner is not blowing out cold air. I checked our thermostat, it is set to cool and auto. The inside temperature in our house is 87 degrees. The thermostat setting is at 74 degrees. I checked the fuse box. There wasn’t any fuses that were tripped. So what I did was reset the internal circuit breaker. I waited 30 minutes before I turned everything back on. No luck.

    1. Hi Angie! So sorry to hear your AC is not working after the thunderstorm. This is why we recommend turning your air off if you are home during storms. I would suggest, if you have not already to turn the AC circuit breaker all the way off and back on again just to make sure the breaker is not off. Is the outdoor unit running at all? You might want to check and see if there is a fuse on the control board of your furnace that is blown. Are you getting 24 volts between R and C and Y and C when the thermostat is calling for cooling? We have lots of air conditioning and heat pump troubleshooting questions with answers and Youtube videos on the following page: We also have an air conditioning and heat pump troubleshooting simplified page that I hope will help you find and fix the problem: We also have lots of troubleshooting advice on the following page: If you have any specific questions please let me know. I hope you have a great day! Steve

  10. Steve, I have a Trane XL90. About 3 years ago the circuit board was replaced. Last week the blower quit working and we smelled “burnt electrical” smell from the vent. Inspection found the blower motor spins just fine but hums. After much research, turns out the the blower motor capacitor was bad. Lots of fun getting it out. I had to cut my horizontally mounted furnace’s 3″ intake and exhaust PVC pipes, remove circuit board and wiring, move the hoses and pressure valves, and remove the inducer motor- all so I could open and slide the blower motor assembly out and replace the solenoid! I mention all this as I still have a problem and wonder if all this movement may be causing it.

    I put everything back together, blower works great in manual mode. When I call for heat, the inducer steps up through various speeds, but as soon as it hits the highest speed, it cuts out and I get a 3 red flash code- inducer error. I checked all my wires and hoses to and from the burner, gas valve, and two pressure switches. In the course of touching everything, it fired once and heated for just a few seconds, then the flames went out and the inducer tried again and again. Without me touching it, every so often it would fire the burners for just a few seconds and then they go out again. Now all it will do is run the inducer motor up to full speed and then cut out.

    The condensate drain is clear, and I had checked the intake and exhaust pipes were clear before I ever started the capacitor job. Any ideas? Thank you for all the other great info on your site (I have read a TON looking for an answer) and thanks in advance if you have time to help!

    1. Hi Keith! Sorry to hear that you had all this trouble replacing the capacitor on your furnace’s blower motor. I do not understand why you had to remove the inducer motor, cut the vent pipes just to replace the blower motor capacitor. Most of the time you should be able to remove the blower door. The blower motor and capacitor would be right there inside the blower door. You also refer to replacing a solenoid so I really do not understand what you were replacing? Most of the time when I smell burnt smells coming from the vent it is the blower motor windings over-heating and this usually requires a new blower motor. Will your blower motor run in the “Fan ON” position from the thermostat? Sometimes the capacitor will fix the blower motor if too much damage has not occurred to the windings of the blower motor. I hope that replacing the capacitor fixed your blower motor problem. Please make sure that your pressure switch is closing and staying closed when the draft inducer is running. If the draft inducer is not sealed, and if you have an air leak then the pressure switch will not close and you will get an error message. Since the inducer is stopping I would think that your problem is with either the control board or the draft inducer motor. I would suggest making sure that you are getting a constant 24 to 28 volts between the W and C (com) terminals on the control board when you have the thermostat calling for heat. If you have a battery controlled thermostat make sure the batteries are new. If you can check the voltage going to the draft inducer. Make sure the inducer is getting 110 to 125 volts the entire time it is supposed to be running. If the voltage is cutting out then I would think you have a control board problem. If the voltage is staying above 110 volts then I would think you have a draft inducer motor problem. Sorry that I can not give you a definite answer. This could be hard to troubleshoot. If you have anymore questions or would like for me to look up parts please send me your furnace’s model number. I suggest that you email me at instead of going through the posts on our site. I hope that you can easily find and fix the problem. Steve

  11. I have a Luxaire gf8050b12mu11a furnace that gave me a 7 red flash (failure to establish flame/no light condition) error on Christmas Eve. We cleaned the flame sensor and she fired right up. Last weekend it happened again so I cleaned the flame sensor and we were back in business for about 24 hrs. I ordered a new flame sensor and installed it but that only worked for a couple cycles. This week I have also replaced the ignitor and the pressure switch. Here is the startup sequence: When there is a call for heat, the fan starts right up the ignitor glows, there is a clicking sound but I can’t hear any gas hissing. The ignitor does it’s light up 3 times and then the system shuts down and gives me a code of 7 red flashes. I did check the power at the gas valve and when the ignitor heats up and I hear the click there is a reading of between 24 and 26V. Any other ideas of what to try? All of my other gas appliances are working just fine so I don’t think its a gas pressure issue. I did order a new gas valve because my only other thought is that the gas valve is stuck?

    1. If your pressure switch is staying closed and you are getting 24 volts to the gas valve and the gas valve isn’t opening up then, yes this sounds like you have a gas valve problem. The gas valve should stay open for at least 8 to 10 seconds before the control board, when it does not sense the flame shuts the gas valve off. I hope you can easily find and fix the problem. Steve

  12. I have a 10 year old York Gas furnace GY8S080B16UH11C. A couple of years ago it started intermittently locking out. The first winter only a couple of times and it flashed 3 red lights indicating the pressure switch is stuck open. I pulled the switch off and messed with it. I checked the tube and found no blockage. Switch seemed to work okay using an ohm meter. I put it back on. The furnace went into lock out maybe one more time that year. Each time I could kill the power and it would usually start okay. That’s been the last two winters. This winters, more specifically the last month or so it started again. I went to look at the error codes and it was flashing 11 red flashes! In the few manuals that I could find online that even showed a York having that many codes 11 flashes meant open switch or blower failure. The open switch lock out could be caused by the high limit being tripped more than 4-5 times an hour or something like that. Or either the blower motor is not working. The thing is it will work fine if I put the fan on continuous run. And the blower has never faltered or made a peep like it was struggling at all. I can tell it’s not quite as snappy as it used to be when it first comes on as it makes a slight howling or singing sound right before it comes up to speed. Other than that it’s been fine. I can even tell when the heat cycle is beginning because the blower will slow down to the heat speed and then after the stat is satisfied it will speed back up to the regular cool speed. The other weird thing was when I went to check the codes the inducer motor was steadily on. Was constantly running and not turning off. I’m leaning towards a new circuit board, but I have bought a new capacitor for the motor and will install it first to see if that will help. I would appreciate any thoughts you may have on my particular situation. Thanks a lot for any help and what a great website! Matt

    1. Hi Matt! Thank you so very much for your question and kind words. It sounds to me that you are on the right track by replacing the capacitor. If the capacitor is weak the motor will not run at top speed. We talk about other problems that can cause poor air flow which would cause the limit to go out on the following page: Our York parts program shows that your furnace uses a 10 MFD 370 volt run capacitor for the blower motor. Here is a screen shot picture that shows some of the parts for your furnace: If it does turn out to be the control board our parts program shows that your furnace uses the S1-33103010000 control board that we sell on the following page: Please see this screen shot picture: I hope the capacitor replacement fixes your problem. I hope you have a great day! Steve

  13. My flame sensor crapped out, so I bought one and while I was at it cleaned the burners, and changed the water pad in my humidifier. My furnace then started intermittently shutting down. (Signal, click, inducer motor runs 2-3 seconds then, off). After a two of these it would start up as normal. This went on for hours, every timethe thermostat called it to come on. After hours of checking possible solutions…… I realized that I had not ran the humidifier this winter so let me try turning it off and unplugging it. Then it stopped! …. Have you ever came across the humidifier causes start & stop cycle problems for a furnace?

    1. Hi! Yes, I have heard of humidifiers causing problems with furnaces sometimes if the low voltage transformer is not strong enough the humidifier will rob or reduce the low voltage power down below 24 volts and cause the control board to have problems. I would recommend that you have a separate low voltage transformer for your humidifier if you do not have one already. Also sometimes installers will connect the humidifier solenoid to run off the control board when the heat is on through the W (white thermostat wire). This can again, rob the system of low voltage power and mess up the anticipation setting on the thermostat. If wired up through the furnace’s low voltage a shorted solenoid valve can cause real problems that could short the furnace out. Again, I would suggest using the furnace’s “HUM” connection or “EAC” connection on the control board or use a separate transformer for the humidifier only. Hope this helps you out. Steve

  14. We have a gas forced air furnace in Minnesota. The furnace has two zones, an upstairs zone and a downstairs zone. We generally do not call for heat in the lower level because we have an in floor heating system that suffices. However, on our upper zone recently the air temp coming from one side of the upstairs registers 130F while the other side of the upstairs registers 70F when the furnace blower motor is circulating warm air. I have cleaned the electrostatic filters and have cleaned the Broan outside air filters. A furnace service company came out and could find anything wrong with the furnace. They also confirmed that there appear to be no dampers in the supply plenums. I have also looked into the cavity between the lower level ceiling and the upper level floor and couldn’t detect a loose vent pipe or hear air seeping from the connection of the pipe and supply vent.

    1. I am very sorry, but I have no idea what the problem could be because it seems like the service company and you have looked and tried just about everything. I would say that the air is being cooled from somewhere. Sounds like the problem is where the duct is picking up the cool air somewhere. I hope that you can find where the cool air is coming from soon. Steve

  15. I have a 4 year old carrier furnace in order for it to run I must shut main power switch off reset it then it will run a few cycles otherwise just hums very quietly with light on front blinking temp in house will fall to 67 even with thermostat set at 72 furnace will not kick on

    1. Hi Mark! Sorry that you are having furnace problems! I would suggest looking on the furnace door or furnace blower door and see what the blink code means. If the thermostat is calling for heat and the draft inducer does not start then you probably either have a relay that starts the draft inducer going out or a bad draft inducer. More than likely a control board problem. I would suggest making sure all connections are good and tight. We have lots of furnace troubleshooting advice on the following page: I would suggest going through the troubleshooting flow chart to see what is wrong: We also have lots of troubleshooting questions and answers on the following page: If you have any specific questions please let me know. If you want me to look up parts please send your furnace product number to our email address: Thanks! I hope you can easily find and fix the problem.

  16. My Carrier 58MXA100 is located in a hard to access area in my crawl space. At 77 years of age it is difficult to crawl under to find out what code it’s generating if it fails. Is it possible I can add an LED, from the board LED and bring it to an interior location where it can be easily viewed??
    I know this would require an electrical background, of which I have. (50 years)

    1. I am sorry, but I have never heard of an add-on device that would send status codes into your home other than use an Arlo wireless security camera like we have here on our home. It will allow you to see what the furnace is doing anytime you want. We have 5 cameras on the outside of our home for security. I do not see why you could not do this with your furnace. That is about the only suggestion I could come up with. Sorry that I can not be much help.

  17. Hi I have a Coleman heat pump unit model#DGAT07OBDF the emergency heat is gas the inducer motor comes on the glow plug lights up stays on but gas valve never opens smart board flashes 5 blinks which says gas valve open not calling for heat. What do you suggest.

    1. Hi Doug! I would suggest that you check all safety controls to make sure they are closed with a volt meter while the furnace is calling for heat. Safety controls would be the pressure switch, limit and all rollout switches. If all the safety controls are closed I would suggest testing the gas valve with a volt meter at the time the gas valve is supposed to be opening. You should get 24 to 28 volts AC to the gas valve for about 4 seconds. If you do not get the voltage then you probably have a bad control board. If you do get the voltage and the gas valve does not open then you probably have a bad gas valve. Here is what I found when I googled “furnace gas valve troubleshooting”…0…1.1.64.psy-ab..10.26.4467.0..0j35i39k1j0i131k1j0i67k1j0i20i264k1j33i22i29i30k1.0.FnbSpMBE9VA I hope this helps you find the problem and get your furnace fixed. Steve

  18. Hi Steve
    Got a Super Quiet 80 Achiever Series by Rudd furnace. It works great when it wants to. Intermittently it will shut down at night and we have to wake up cold in the morning. Troubleshooting reveals the first burner of the 3 always lights like it is supposed to, but the other 2 don’t always follow suit. Sometimes they light off and other times they try twice , fail , and the furnace shuts down till we reset everything and start over. Service tech came out, cleaned the ignighter, checked everything he could think of and it seemed to work well while he was here. He said we could possibly have a low gas pressure problem.
    I guess I’m looking for some professional input before calling him back and start the high priced guessing game again.
    I would really appreciate any input you could give me. Thanks in advance !! Joe

    1. Hi Joe! Sorry to hear that you are having trouble with the burners not lighting all the way across sometimes. This probably occurs most often when the furnace is cold and trying to light and start. If the service tech did not already do this I would suggest that you turn the furnace and gas off, take the burners out and blow them out with compressed air and use a wire brush to clean them out on the outside. I would unscrew the gas orifices and blow them out with compressed air. I would suggest either cleaning or replacing the flame sensor while you have the burners out. If you need part numbers please send me your furnace’s model number and serial number to our email address: and I will give you the part numbers. If you are still having problems with the two burners not lighting properly I would suggest adjusting the gas pressure up on your gas valve. I would suggest turning the adjustment screw counter-clockwise 1/4 a turn and test to see if this helps. Be ready to turn the furnace off with the power switch if the furnace does not light right away because if the gas valve is not adjusted properly it can cause delayed ignition (small explosion) and this is not good. I have seen delayed ignition blow furnace doors off! There is a good Youtube video on how to properly adjust gas pressure on the following page: Your problem sounds like either dirty burners or gas pressure on the gas valve set too low. I hope you can find and fix this problem soon! Steve

  19. Hi, I have a Coleman Evcon EB12E electric furnance. My problem is The fan will automatically come on, but the elements will not come on unless, I turn the thermostat up a few degrees, when the room gets warm the elements turn off but the fan continues to blow and if left blowing it blows cold air, so I have to turn the thermostat down to turn the fan off. I have replaced the the sequence switch, and that didnt solve the problem. Your help would be greatly appreciated.

    1. Hi Kathy! This sounds like you might have a thermostat problem since you said that the heating elements will not come on until you turn the thermostat up a few degrees. If you have a W1 and a W2 on the thermostat then maybe the W1 set of heaters are not working and you only get heat when the W2 heaters are activated by the thermostat. The thermostat should send 24 to 28 volts AC through the “G” green thermostat wire to turn your fan relay or fan relay sequencer on to get the fan to turn on as soon as the thermostat senses the need for heat and turns on the blower. The “W” white thermostat wire should turn the electric heaters on. I would suggest making sure that you are not gettng 24 volts through the G wire when the thermostat is turned down where it should not be heating anymore. So you would test between G and C (com) to make sure you are not getting 24 volts to the fan relay sequencer when the thermostat is turned down where the heaters should not be coming on. Most electric heat thermostat are set to automatically turn the fan on through the G (green wire) when the electric heaters come on. Another thought is that maybe you have a W1 and a W2 on your thermostat connected to two levels of electric heaters and when the W2 heaters come on and you feel heat, but maybe the W1 bank of heaters are burnt out or have a problem so when the thermostat turns W1 heaters on all that you feel is cold air. If you have a W1 and W2 on your thermostat make sure both sets of electric heaters are working. Another thing to think about is that some of the sequencers have a long delay on them which could be 2 to 3 minutes. The sequencer should eventually shut the fan off after 2 or 3 minutes after the 24 volts is removed from the coil voltage of the sequencer by the thermostat. Here is a link to a real good Youtube video on how sequencers work. I hope this gives you some things to look for that might be the problem. Hope you can find and fix the problem soon! Steve

  20. put new control board in furnace the blower motor will only work when you put the fan on on thermostat it is a trane furnace

    1. Depending on how old your furnace is the control board usually times how long before the blower comes on in the heating mode. If you have an older furnace with a mechanical fan/limit control then this could be the problem. The mechanical fan/limit control could be broken. Please make sure that when you installed the new control board that you have one of the blower speed wires attached to the “Heat” connection on the control board if the board has a “Heat” designated terminal. I would think it is a control board problem if the board does not send 120 volts to the blower motor in the heating mode. I hope you can find and fix the problem. Steve

  21. I have a carrier gas furnace where the hot surface igniter will not work. Read on on your site on how to check it and found it was reading over 120 ohms and had a few white spots. I thought I had found the problem but no! After replacing it with a new identical one and turning everything back on, it starts to work as expected and it gets to the point where the gas starts but I do not see a glow from the hsi and after a few attempts it shows code 34 again. Any clues on what I should check next?

    1. Hi George! Sorry that you still can not get the ignitor to glow after replacing it with a new ignitor. I would like to suggest that you check to make sure all rollout switches, pressure switch and your limit switch is closed. We discuss this problem in a post we have on the following page: I hope that it is a simple as pushing in on one of the buttons on one of the rollouts and you do not need a control board. I would also suggest that you make sure all connections are good and tight on the control board and any other connections. I hope you can easily find and fix the problem. Please send me your product number if you would like for me to look up parts to our email address:

  22. I have an American Standard 2/4TEC air handler. When the furnace comes on to heat the blower comes on as normal but when the electric coils kick in I hear a buzzing noise that has gotten louder, sounds like a possible relay or transformer? The unit seems to be operating normally, just a very noisy buzzing sound. I can not find a wiring diagram for this unit.

    Model# 2TEC3F48A1000AA
    Serial# 6083X8U1V

    Please advise on what the issue might be. Thank you.

    1. Hi Ron! You might have a noisy sequencer or circuit breaker. I would suggest turning off all the power and checking to make sure all the high voltage wires are good and tight. A circuit breaker that is arcing (going bad) can cause a noise like you describe. You might try taking the cover off your air handler and see if you can tell where the noise is coming from. You can usually tell if it is a transformer that is buzzing. Sometimes just tightening a transformer down with help stop the noise. I would not suggest running with the cover over for more than a couple of minutes because if you have a heat pump this could cause high head pressure which is not good for the outdoor heat pump. If you find a part that you need I will be glad to give you a part number. Steve

  23. Is there an easy way to clean some corrosion on a coil of the inside air handler ?

    1. Hi Jeff! No sir, I do not know of an easy way to clean an evaporator coil. We have a good video on the following page which shows how to clean a coil on the following page: I always removed the blower motor so it will not get damaged by water (if it is and up-flow furnace). Used coil cleaner, a spray bottle of water, a fin comb tool (to clean the fins) and a wet vac with a brush to clean the under side of the coil. Sorry that I do not know an easy way. I know that you will see a tremendous difference in air flow and better cooling if the coil is good and clean. Thanks for asking this question. Steve

  24. I have a Goodman GMV90905DXA that is about 12-13 years old and it runs fine. I was changing the filter and had the fan cover off and noticed a little bit of water in the rear corner of the fan section (opposite the motor/control board).

    I found that the issue is that at the bottom of the burner section water (condensate) is collecting on the flat metal bottom of the burner section. It is not coming from the plastic cover but it looks like it is coming from between the base of the burner unit and the bottom of the sheet metal (under the plastic cover). The condensate drains were working but I cleaned out the tubes/trap on the outside of the unit just to make sure. I have taken the burner section cover off and watched to see exactly where the leak is but when I am watching there is no leak (I let it run/watched for 30+ minutes) If I check the next day though there is a small puddle on the base of the burner unit about 3-4 inches in diameter on the far left side and a quarter size rust spot (which makes me think it has been going on for a while). I would appreciate any insight you may have on what this is and what to do to fix it before it creates a really big problem. There is no leaking on the outside of the unit and no issues with it starting, running, etc. – Thanks

    1. Hi John! This sounds like it could be a secondary heat ex-changer leak. About the only way I found to find leaks in secondary heat exchangers is to take the blower out and take a look at the secondary heat exchanger. Several times I have had to replace rubber hoses that come off the heat ex-changer or replace the secondary heat ex-changer completely. The heat ex-changer should have a life-time warranty. It is a pain replacing it because on the ones I replaced the hole front of the furnace has to be removed. You might want to have a tech check this problem out. Of course they will want to sell you a new furnace. I hope you can easily find and fix the problem. Steve

  25. Hello,
    I like your website . Lots of info
    I have 2 level Goodman hvac system . My upstairs heating works fine . My
    Downstairs heating has stopped working . I saw the upstairs furnace in the attic.
    I cannot find the downstairs furnace . I cannot find it . There are two condenser
    Units outside the house . I also have crawlspace with ducts inside . How do I fix
    My heating problem downstairs . The system is 12 years old .
    Thank you for your help .

    1. Hi! If your duct work is in the downstairs floor then more than likely your downstairs furnace is located in the crawl space. You will definitely need to find the downstairs furnace in order to work on it. When you do find it…We have lots of furnace troubleshooting advice on the following page: I would suggest going through the troubleshooting flow chart to see what is wrong: We also have lots of troubleshooting questions and answers on the following page: If you have any specific questions please let me know. Thanks! I hope you can easily find and fix the problem. Steve


    1. Hi Mr. Bray! The part number for blower motors are usually located on the motor label which is glued to the motor body. I hope you have a great day! Steve

  27. I hear water sloshing in drainage tube while heat is on electric furnace.

    1. Hi Mr. West! If it is actually water that you are hearing then I would suggest trying to blow the drain tube out with compressed air. I am sorry, but I really do not know anything much else to recommend.

  28. Hi. I have a two year old white Rogers gas valve on my furnace. The pilot lights and stays lit but burners don’t. Tried bypassing thermostat..nothing happens. Turned valve to off, pilot stays lit. Disconnected electric, pilot stays lit. Had to turn gas off completely for pilot to go out. Wassup with that?

    1. Hi Neal! Standing pilot furnaces usually have a thermocouple which senses the pilot flame. We discuss how this works on the following page: The pilot flame will continue to burn until the flame is blown out and the thermocouple cools down. I would suggest that you test the gas valve with a volt meter. Set your thermostat so it is calling for heat with the pilot lit. Test the wires going into the gas valve to see if you are getting 24 to 28 volts to the gas valve if you are and the gas valve is not opening then you have a gas valve problem. If you aren’t getting 24 volts to the gas valve then you could have a thermostat problem, thermostat wire problem, limit, pressure switch or roll-out switch could be open or a low voltage transformer problem. We have a troubleshooting flow chart that I hope will help you out on the following page: I hope you can easily find and fix the problem. Steve

  29. I have a Goodman AC/propane heater combo. It is 12 years old. What happens is when it calls for heat the blower comes on. after a short time the ignitor causes the first burner tube to fire, (it is a 3 burner tube set up), but the next two tubes fail to fire causing the sensor to shut it down. I have manually ignited the next two tubs and it works perfectly. I usually manually ignite the last tube and when I do that the middle tube will fire. The unit is a goodman, model # PGJ0420751A. I have not cleaned any of the three orfces yet. The fact that I can manually light the burners tells me propane is coming through. I have only guessing but the three flames all seem to be of the same intensity.

    1. Hi Mr. Robinson! This sounds like either the gas runner between the burner tubes is dirty or stopped up or you do not have enough gas pressure to ignite the other two burners properly. LP Gas is very critical on getting the right pressure to burn correctly. This should be adjusted with a manometer. Here is what I found when I Googled the subject: I would also check the orifices to make sure they are not clogged up too. I would start by turning off the power to your unit and blowing out the burners and gas runner with compressed air. I hope this fixes your problem. Steve

      1. Thank you Steve, I just noticed the runner between the burners and they did not seem to be lit. I am guessing I can blow then out without removing the burner unit. I am having a tech come out tomorrow and check if I have the correct pressure at the Propane tank regulator and the regulator at the house. I was concerned I did not have pressure also. We shall see. I will let you know the results. Again thank you. Boyd Robinson

      2. Hi Mr. Robinson! I hope that the cleaning and the gas pressure adjustments fix your problem. Please let me know when you find out what the problem was. Thanks! Steve

  30. my daughter made thee part of a plug piece that fits togethr bitsbthe plug piece go down thee vent in her bedroom how do i get it out

    1. Hi Terry! If the plug is not too far down the vent I would suggest using a vet vac with a long hose to try and retrieve the piece out of the vent. Sometimes a small mirror and a flash light might help you in viewing the lost piece. If the piece slipped too far into the vent to use a wet vac then you might have to take the vents (duct work) apart to retrieve the lost plug. I have you can get it with a wet vac. Best of luck! Steve

    2. Steve, Boyd Robinson here, I don’t know if this will be on the right post or not, but my problem was the dirty runner between the 1st and 2nd burner, and the 2nd and the 3rd burner. Rust mostly, cleaned out the opening and works fine. Thank you for your help. I had been having problems for two years and then it just quit working.

      1. Hi Mr. Boyd! Glad to hear that you fixed your furnace by cleaning the dirty rusty runner between the burners! Thank you so very much for letting us know this fixed your problem. I hope it will help others out in fixing their furnaces. Thank you so very much for posting this! Steve

  31. it s winter, upper mich, my ladyfreind sets her furnace at 60! the temp inside is 59 the furnace kicks in but does not blow heat, shuts down, and repeats another cycle the furnace works fine when its set above the inside temp of the home, what damage will this cause to the furnace , if any ?

    1. Hi Mr. Scheiding! Thanks so much for asking this question. It is not good for the parts inside the furnace to short cycle. Parts have just so many cycles in them. The short cycling can cause premature failure. Wow! 60 is pretty cold! The thermostat might not be programed to go that cold. Of course, you would need to determine what is causing the short cycling. Is this a thermostat problem, a flame sensing problem etc? We have a furnace troubleshooting flow chart that should help you find the problem on the following page: We have lots of furnace questions and answers on the following page: I would suggest starting my testing between W and C (com) on the furnace control board to see if the thermostat is cutting the furnace off and on. Please make sure you are getting a constant 24 to 28 volts AC between the W and C (com) terminals on the control board when the thermostat is calling for heat. If you aren’t then this is a thermostat problem. If it is a thermostat problem then you would need to get a new thermostat or try to set the thermostat degree difference or anticipator up so the themostat keeps the furnace on longer. If this is a flame sensor problem I would suggest trying to clean the flame sensor. I hope you can easily find and fix the problem. I hope you have a blessed day! Steve

  32. I have a Carrier 1986 Model 58GS100-150CA furnace. Lately the main burner ignites and then immediately shuts off then re-ignites several cycles. Finally it will remain on and run normally. I cannot locate a flame sensor on this unit. I do not believe it has one. So what else could cause this problem?

    1. Hi Mike! This could be something as simple as a dirty 3-wire pilot burner. I would suggest that you try to clean the 3- wire pilot burner out with compressed air. Our Carrier parts program shows that your furnace uses the LH680005 three wire pilot burner that we sell on the following page: I hope that cleaning the pilot burner fixes your problem. If not you might need a new pilot burner. I would also recommend that you check are wire connections and grounds to make sure they are good and tight. Steve

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