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Problem: Why I am not getting 24 volts to the contactor? Where does the 24 volts come from?

happy AC small

Problem: Why I am not getting 24 volts to the contactor? Where does the 24 volts come from?

Answer: The 24 volts comes from a low voltage transformer. Please see the pictures of the two transformers below.  The transformer has a primary (high voltage side) and a secondary (low voltage side).  The high voltage side takes 110 to 240 volts AC and transforms the voltage to 24 to 28 volts AC. If the contactor is not getting the 24 volts to the contactor coil then it could be a time delay relay (if the unit is equipped), thermostat problem, transformer, safety control (low on refrigerate), or wiring problem. I would like to suggest that you turn the power off to the unit and check all your connections to make sure they are good and tight. You can turn the power back on and set the thermostat so the system is calling for cooling (AC ON).  You could test the contactor with a voltmeter to see if you are getting 24 to 28 volts AC to the contactor 24-volt coil. If you are not getting any voltage to the contactor coil then this could be a blown fuse on your furnace or air handler control board. Please see the picture of the control with the fuse below.  If the fuse on your control board is blown then you probably have a short in the thermostat wires or another control in the furnace or outdoor unit.  We sell a universal time delay relay on the following page: Please click here if you would like to see the universal time delay relay we sell.  We sell transformers on the following page: Please click here if you would like to see the Low Voltage Transformers we sell.  Many air conditioners and heat pumps have low and high-pressure safety switches on them to protect the unit from damage if the system pressure is too low (low refrigerant charge) or too high (dirty outdoor unit, slow or bad condenser fan motor). If your unit is low on charge (I find most often) the safety switch will not allow the unit to start (contactor will not engage). You will need to call a service tech in order to check the charge on your unit. We sell contactors on the following page: Please click here if you would like to see the AC contactors that we sell. Please send us your unit’s model number if you would like for us to look it up and see which OEM contactor your unit requires. Our email address is: arnoldservice@gmail.com  Below we have a real good informative YouTube video made by grayfurnace man which shows how to troubleshoot and test a contactor. If you have any questions we will be glad to answer them. Please email us: arnoldservice@gmail.com or comment in our comments section below. We would love to help you out and have your business!

 

Universal Low Voltage Transformer  Carrier Bryant Furnace Transformer HT01CN001

Troubleshooting Gas & Electric Furnaces

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Problem: I am going through an ignitor almost every year. What could be the cause for my furnace cycling too much?

Problem: I am going through an ignitor almost every year. I think it is because my furnace cycles off and on too much. What could be the cause for my furnace cycling so much?

Answer: Below we have listed some reasons why your furnace ignitor might be going out so often. We hope this will help you from having to replace your ignitor so often!

*Please remember to turn off all electrical power to your HVAC system when trouble shooting or working on HVAC equipment. We most certainly do not want to see anyone get hurt or damage their equipment!

 If you need a furnace ignitor: Please Click Here to go to Our Furnace Ignitors Page If you have questions or would like for use to look up parts for your furnace, please email us anytime. Our email address is: arnoldservice@gmail.com. For Bryant and Carrier equipment we will need product numbers. For Ruud and Rheem equipment we will need both the model number and serial numbers.

Below are listed some reasons that might cause your ignitor to go out prematurely:

  1. Handling the ignitor improperly by touching the gray glass part.
  2.  Installing an ignitor that is not made for the furnace.
  3.  High home line voltage. Check your voltage to see that you are in the 110 to 125 volt range. Anything over 125 volts is going to cause premature light bulb failure and furnace ignitor failure. Call your electric company if you are getting high voltage in your home. Your electric company should be able to place a transformer on your line to lower your line voltage.
  4. Debris from the heat exchanger or bugs/spiders can get on the ignitor while the furnace is not calling for heat and when there is a call for heat the debris/bug can short the ignitor out. It is a good idea to keep your furnace and heat exchanger clean so this does not happen.
  5. Moisture from a leaking air conditioner can cause water to drip down on the ignitor and electrical parts and ruin the parts. Please make sure your air conditioner’s condensate line stays open and your AC coil does not leak.
  6. The ignitors have just so many on off cycles in them. We have listed below some of the reasons why furnaces cycle off and on too much.

Below are listed some reasons why furnaces cycle off and on too much. It this cycling occurs it will cause premature part failure and can cause high heating bills.

1. Over-sized furnace. A furnace that is too large for you home cycles too much. If your furnace is sized properly on your coldest day the furnace should run almost continuously. Shutting off very few times. I went to an HVAC training meeting on energy conservation. The speaker said, “The inefficiency of a furnace is in the On, Off cycling.” He made this statement that on the coldest day your furnace should almost run continuously if sized properly.

2. A dirty filter or blower squirrel cage causes too much cycling. Your furnace will go off on high limit continuously because it is not getting enough airflow through the heat exchanger. The furnace goes off on high limit to keep from overheating the furnace and possibly causing a fire. This is why it is very important to keep those filters changed.

3. A dirty restricted air conditioning evaporator coil causes restricted airflow that causes too much cycling. Make sure your coil is not stopped up on the underneath side. I usually have to take off the coil end plates and use a vacuum cleaner and coil cleaner to get all the lint and dirt off. Make sure you clean in the direction the coil fins are running. If you do not, it will bend the fins over and cause more restrictions. A good tool to use is our air conditioner fin coil cleaning tool.

Please click here to go to our air conditioner fin comb tools page.

Please click here to see the AC evaporator coil cleaner that we sell.

4. Improper thermostat heat anticipator setting. Look at your gas valve and see the amp draw. Set you thermostat’s anticipator setting to this amp draw plus one amp more. If your gas valve says, “.4 amps” then set your thermostat to “.5″ amps. This will give you a little longer run time and a longer off time. If you have an electronic thermostat: Many of the electronic thermostats have temperature differential adjustments or like on the Honeywell thermostats have screws where you can adjust to make your furnace cycle a little longer.

Below we have a pictures on the left of a label off a White Rodger’s gas valve and on the right a Honeywell Round thermostat anticipator. The label shows that this White Rodgers gas valve model #38C03 Type 300 draws .23A or .23 amps. The anticipator shown in the picture on the right is set on .4 amps. If I were using this White Rodgers Gas Valve and the Honeywell Round thermostat I would set the anticipator one amp more than the gas valve draws, on .3 or a little past the.3. The little copper looking pointer can be moved to make your furnace stay on longer by using your finger to move the pointer. Again, you should look at your gas valve’s amp draw to determine your setting.

White Rodgers Gas Valve

            anticipator

6. Too much gas pressure causing the furnace to overheat because too much heat is being produced. This causes the furnace to cycle too much on high limit. Does your furnace’s gas pressure sound like a jet when it is running? Your gas pressure on your gas valve might be set too high. This produces too many BTU’s or too much heat. I would recommend a HVAC technician adjust this problem. Turning the adjustment screw clockwise gives more pressure. Counter clockwise gives less gas pressure. If you attempt to adjust this yourself, do not adjust more than 1/4 turn clockwise or counter clockwise. Delayed ignition, blow back,  and a mini explosion, could occur.  Again, I would recommend an HVAC technician do this adjustment. Getting this adjustment right will save you gas utility costs, and wear and tear on your furnace in the long run.

Valve with pressure screw cap removed

7. Your furnace flame sensor might need cleaning. If the furnace flame sensor needs cleaning or replacing the gas burners will not always stay on the first time. If the furnace is having flame sensing problems the furnace burners will light for 8 to 10 seconds then cut right back off. The cycle will start again and again. Usually the furnace will try to light 3 times then the furnace will go into lock out until the power switch on the furnace is reset.  This short cycling will cause the furnace and ignitor to cycle off and on too much. You can usually fix a flame sensor problem by cleaning the flame sensor with steel wool or light emery cloth sand paper. If you need a new flame sensor:  Please click here if you would like to see the furnace flame sensors we sell. If you have questions or would like for us to find out which flame sensor your furnace uses please email us anytime: arnoldservice@gmail.com Below we have a real good informative YouTube video made by Fix It Home Improvement Channel which explains ignitor and flame sensor operation and how to replace an ignitor and flame sensor. Thanks to Fix It Home Improvement Channel for making this informative video!

Below we have a Youtube video made by hvacrepairguy showing how to replace an ignitor. Thanks to hvacrepairguy for making this informative video.  If you have any other questions please feel free to email mail us: arnoldservice@gmail.com or comment in the comments section below.

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Problem: Why does my furnace rollout switch have to be reset so often? Why do rollouts have different temperature differences?

limits three

Problem: Why does my furnace rollout switch have to be reset so often? Why do rollouts have different temperature differences?

Answer:  The rollout switches and limits are determined by the engineers during the furnace building and testing process. Different areas of the furnace are allowed different heat measurements before they are determined to be safe or unsafe. If the furnace limit or rollout switch senses that over-heating occurs then it trips the rollout switch to prevent an unsafe over-heating condition.  Many times when a limit or rollout trips or opens up it will tell the furnace control board that the furnace has overheated and the blower on the furnace will run continuously to cool the furnace down until the power on the furnace is turned off and back on again. If your limit goes off again I would strongly suggest you get your furnace checked out to make sure something is not stopped up and to make sure you do not have a leak in the heat exchanger. This can be very dangerous! We sell limits and rollout switches on the following page:  Please click here if you would like to see the furnace limits and rollout switches we sell. Below we have a really good Youtube video that shows what happens when a heat exchanger or vent gets stopped up and gas flames roll out of the front of the heat exchanger. The rollout switches are placed as a safety device around the burner area to sense the hot flame or hot exhaust thus shutting down the furnace so you do not get a fire or get carbon monoxide poisoning. The video below shows an exaggerated version of what furnace flame rollout looks like. If you feel any heat coming out of the front of the furnace or if your rollout switches are going off then I would suggest calling a service company to make sure your furnace is safe. If a furnace has a leaking heat exchanger you can feel more heat come out of the furnace when the blower on the furnace starts up because a crack in the heat exchanger will allow blower air to enter the heat exchanger which creates a dangerous condition. Below we have a picture of two limits and one rollout switch. The push-button manual set rollout switch is located in the middle. We also have another really good informative video made by RepairClinic.com which shows how to replace a rollout switch. Thanks to RepairClinic.com for making this informative video! We also have another really good YouTube video made by AC Service Tech LLC that explains how to test and troubleshoot rollouts and limit switches. Thanks so very much to AC Service Tech for making this excellent video! If your rollout switch is having to be reset please call a service company to check your furnace out. If you have any other questions please feel free to email us: arnoldservice@gmail.com or comment in our comments section below. We would love to have your business!

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Problem: Gas furnace will not ignite the gas to produce heat for our home. What could be the problem?

broken ignitor

Problem: The gas furnace will not ignite the gas to produce heat for our home. What could be the problem?

Answer: Your furnace probably has a bad ignitor.  The following sequence of operation is what I see most of the time when an ignitor is bad.

1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8″ in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lockout condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas.
Solution: You probably need to purchase and install a new ignitor. Please click here if you are interested in seeing the furnace hot surface ignitors we sell. I would suggest that you inspect your ignitor closely for cracks. Make sure you do not touch the ignitor (grey glass black part) with your bare hands. You can handle the ignitor by the white porcelain base of the ignitor.  If you do not visibly see a crack then you can test the ignitor with an ohmmeter to see if it is good or bad. Set the multimeter so it can properly measure the resistance of 10 to 200 ohms. Disconnect the hot surface ignitor from the control board and measure the resistance. A good hot surface ignitor will have a resistance of 40 to 90 ohms. Greater than 90 ohms indicates a failing or failed hot surface ignitor. Please see the video below which shows how to test an ignitor with an ohmmeter. If the ignitor looks and tests to be good then you could have a furnace control board problem or a limit, rollout switch, or pressure switch problem.  The furnace’s control board might not be supplying the voltage to the ignitor. Please click here for our Furnace Control Boards Page.  If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then I would suggest that you clean your flame sensor with light sandpaper (emery cloth) or steel wool. You might need a new flame sensor, but most of the time they can be cleaned and will work well after cleaning.  We sell flame sensors on the following page: Please click here if you are interested in seeing the furnace flame sensors we sell.  We sell hot surface ignitors on the following page: Please click here if you are interested in seeing the furnace hot surface ignitors we sell. We sell 56 different ignitors. Please send your furnace make and model number if you would like for us to look up the ignitor or other parts for your furnace. If you have a Bryant or Carrier furnace we will need the product number in order to look up parts. If you have a Rheem or Ruud we will need both model number and serial number.  Our email address is arnoldservice@gmail.com You can also leave a comment in the comments section below and we will respond to your comment ASAP. Below we have two really good informative Youtube videos produced by Fix It Home Improvement Channel and Repair Clinic on how to test, replace a furnace ignitor and flame sensor. Thanks to Fix It Home Improvement Channel and Repair Clinic for making these informative videos.



You Can Search Our Site for More Troubleshooting Problems with Answers, Heating, Air Conditioning Parts and Supplies in the Google Search Box Below:

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Why does a motor or compressor need a capacitor to run properly? What actually does a capacitor do?

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Hi!
Thanks for your interest in our website! Great question! I know there are many technical variations in explaining how capacitors work. This is the way my HVAC instruction explained to us how a run capacitor works. There is an easy understandable explanation. On alternating current (AC) the current alternates on the voltage from zero to 110 or from zero to 220 volts 60 cycles per second. The run capacitor throws a stored charge in when the voltage reaches the zero point and keeps the voltage steady instead of all the up and down voltage drops. This makes the motor or compressor run smoothly and more efficiently. This is easily seen on an old oscilloscope where you can see the AC current going up and down. 60 cycles per second is pretty durn fast! It is amazing! I hope this answers your question. If you have any other questions please email us anytime: arnoldservice@gmail.com. I hope you have a blessed day!
Sincerely, Steve Arnold
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Problem: How do I wire up a dual round capacitor?

happy ac

Problem: I forgot how to wire up the dual round capacitor that I purchased from you. How do I go about wiring it up so it doesn’t blow the capacitor up again?


Answer: Thanks for your interest in our website! You would need to look at the wiring diagram that came with the unit. Usually, the wiring diagram is glued to one of the panels on the air conditioner. Hope you can read it. Round dual capacitors on the top should be marked: Herm, Com, and Fan. Rule of thumb on wiring the capacitor is: Herm on capacitor goes to the start winding on the compressor, Fan on capacitor goes to brown fan wire that goes to the fan, and Com on the capacitor comes off one leg of the contactor to provide power to the capacitor. There is usually more than one wire connected to the Com terminal. The Com terminal is used so other components like the fan motor of the air conditioner can steal power from the Com connection. Below we have two YouTube videos that explain how to troubleshoot Air conditioner and heat pump capacitors. If you have any questions please email us anytime: arnoldservice@gmail.com. God bless you and your family today and always. Sincerely, Steve Arnold


You Can Search Our Site for More Troubleshooting Advice, Problems, Heating, Air Conditioning Parts and Supplies in the Google Search Box Below:

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Problem: What to look for when a capacitor is bad? My unit will not do anything!

comparison good  bad oval capacitors

Problem: What do I look for when a capacitor is bad? My Air Conditioner unit will not do anything!

Answer: Capacitor problems are probably the second most common problem that I see every summer in our 28-year-old HVAC business! Air Conditioning and heat pump systems low on refrigerant charge are the most common problem that I see. Changing out a capacitor is a simple, inexpensive problem that almost all homeowners can fix easily if you are good with your hands and have the right capacitor. Weak or bad capacitors can also cause blower motors to not run or to run slow. We have three really good YouTube Videos near the bottom of this page that explain how to replace and troubleshoot an air conditioner’s capacitors. We also have a really good YouTube Video made by AC Service Tech that shows how to find the capacitor rating if the capacitor is rusted so bad that you can not read the specifications off the capacitor.  We sell over 80 different capacitors on the following page: Please click here to see the capacitors we sell.

What to look for when a capacitor is bad:

The Air conditioner outdoor unit will not come on. Either the outdoor fan does not run, the compressor does not run, or both the fan and the compressor do not run. You have checked and reset your circuit breaker. The outdoor unit still does not come on. You can hear a little humming sound inside the unit which is the low voltage contactor humming. Please pull the disconnect and disconnect the power to your outdoor air conditioning unit.

*Please make sure your electrical power is off before working on any air conditioning equipment. You take the door or cover off your outdoor unit’s control box and find a bad, swollen run capacitor. EPA stopped allowing manufacturers to produce capacitors with cancer-causing PCBs. Since they stopped allowing the use of PCBs in the capacitors and now capacitors have a shelf life. Many times I see capacitor problems that will not allow the compressor or the fan to come on. Many times you can clearly see that the capacitor is bad because it is swollen or even blown apart with capacitor oil everywhere! Please see the pictures below.  Sometimes you need a special meter to test the microfarad (MFD) or UF rating. A capacitor tester. Please click here if you are interested in seeing a real good Supco Capacitor tester.

“MFD” and “UF” mean the same thing, “Microfarad”. Many times you will see a “UF” rating on the capacitor instead of “MFD.” Yes, these two abbreviations mean the same. Most of the time you can tell that a capacitor is bad because it will be swollen up. Please see the picture below for the comparison between a good and bad dual-run capacitor. We call them dual because the capacitor helps run both the fan and the compressor. If you have any questions please email us anytime or comment below. Our email address is: arnoldservice@gmail.com

*Tip: When identifying the capacitor that you have, you might see the rating stated in “MFD” or “UF.” “MFD” and “UF” mean microfarad rating and mean the same. Below we have some pictures of bad round and oval capacitors. Sometimes capacitors are weak and need to be replaced. If you do not have a capacitor tester…I would suggest taking the capacitor to an appliance parts supplier and ask them if they would be kind enough to test the capacitor for you. Please click here if you are interested is seeing the over 80 different capacitors we sell. We would love to help you out and have your business!

Bad round dual capacitor on the left.
Bad oval capacitor on the left.

Below we have a real good informative video which shows how to troubleshoot and repair an air conditioner’s contactor and capacitor. Thanks to Kevin Miller for making this informative video!

Below we have a real good informative and educational video on “Dual Capacitor Checkout Procedure” made by Ron Walker. Thanks so much to Mr. Walker for making this informative video!

Below we have a really good YouTube Video made by AC Service Tech that shows how to find the capacitor rating if the capacitor is rusted so bad that you can not read the specifications off the capacitor.


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