HVAC Troubleshooting

Below we have quick page links to our HVAC troubleshooting pages. We hope these pages will help you answer and solve just about any HVAC problem. Please email us anytime if you have any questions or need our advice. Our email address is arnoldservice@gmail.com We would love to try and help you troubleshoot and repair your air conditioner or furnace!

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26 thoughts on “HVAC Troubleshooting

  1. On 12/29/2021, I had a Carrier Comfort 2.5 ton 14 Seers heatpump and air handler split system installed. During January very cold temperatures the outside heatpump often stops to defrost kicking in the auxiliary heat in the attic air handler. When auxiliary heat stops, I hear an evenly spaced rythmic drip, drip, drip noise behind the walls of my bathroom closest to the air handler location in the attic. It seems heater coils, metal either are cooling, or freon pressure problem or water dripping like in a faucet inside the air handler. But, there should not be any condensation during heat mode in the air handler. So, I am concerned for safety and integrity of air handler. I greatly appreciate your opinion.

    1. Hi Miriam! I would suggest that you try to inspect the air handler for water leaks or have the installing company come out and inspect your air handler. I am guessing that when the unit goes into defrost mode the indoor evaporator goes into Air conditioning mode, thus the indoor evaporator coil gets cold and could produce moisture like in the summertime. Normally, evaporator coils do not produce much water during defrost in the wintertime, but it is possible that the coil is producing water when defrosting then leaking out of your air handler. To be safe and not cause damage to your home I would either inspect for water leakage or have your installing company out to make sure it is not leaking. This sound could be caused by expansion and contraction of the ductwork, but if you feel is it a water dripping noise then I would most certainly have it checked out. I recommend that heat pump owners go to emergency heat when the outdoor air temperature is going to be below 32 degrees for an extended time because the heat pump will get into a long constant run cycle when the outdoor temp is below 32. We have a heat pump and I always go to emergency heat (heat pump outdoor unit does not run) when the temperature is going to be below 32 degrees overnight or during the day. This will save your heat pump from wearing out so soon and you will feel warmer. Of course, this might raise your electric bill some, but you will feel warmer and you will save the wear and tear on your outdoor heat pump unit. We have a post about this question on the following page: https://arnoldservice.com/question-is-it-best-to-turn-off-heat-pump-and-go-to-emergency-heat-when-real-cold-out/ I hope this answers your question. Steve

  2. Hello Steve,
    I’m Dwayne. I have a friend who has a Goodman hvac heat pump system at his house. The system’s air handler with heating elements is a Goodman model ARUF37C14AA. The heating elements are controlled by a 40amp double pole contactor that has a 24 vac coil which receives it’s power source from the secondary side of a 240 vac primary/24 vac secondary control transformer via the PCB board and thermostat. The transformer is rated for 40VA. The PCB board is a standard PCBFM103 circuit board.
    My friend purchased an ionizer type electronic air cleaner manufactured by Aprilair and would like to install it in the duct on the input side of the air handler. The model of the eac is Aprilair Model 5000. April air provided a page in the manuel they provided that showed using an eac power point to power up a 120 vac/24 vac control transformer to be able to power the unit if it were being installed to be put in service for use with a humidifier. The page has two illustrations and the second or bottom illustration states not to wire in the transformer with the furnace (air handler) blower circuit. Of course it would not make any sense for anyone to attempt to wire in a 24 vac power supply to a circuit board that has a time delay relay consisting of a common and a normally open and normally closed set of contacts that is already wired and receives a power source of 120 vac from one side of the air handler units 240 vac feed, and is already control by the existing 24 vac that is supplied to the circuit board from the existing control transformer. I suggested to my friend that he considered purchasing a 240 vac/24 vac control transformer that had a higher va rating, and to consider replacing the existing 40va control transformer and adding a definite purpose 120 vac single pole contactor that has unbroken termination points for the neutral and that also has a 24 vac coil. I suggested to my friend that the single pole contactor should be able to be controlled by the fan call or command wire from the thermostat via the circuit board. I suggested to my friend that some heat resistant type 3 conductor wire could be used to go from the added 120 vac single pole contactor installed in the electrical compartment of the air handler, to a 120 vac duplex receptacle that could be installed near the input end of the air handler so that the 120 vac cord that is on the Aprilair 5000 eac could be plugged into. My friend purchased a 240 vac/24 vac 75va control transformer while thinking of do this the ways that I suggested to him. The PCBFM103 circuit board is fused by a 3 amp fuse and does not have any eac or hum connection points on it, so I suggested to my friend that he may should have considerd only upsizing the existing 40va control transformer, to a 50va or no higher than a 60va potential control transformer. I was wondering what your thoughts or opinions might be on the suggestions I gave my friend in being able to accomplish getting the Aprilair eac installed, and would you happen to know if there may be a circuit board that could be purchased that has an eac connection point to replace the PCBFM103 circuit board that came with the unit that does not have any such connection point, or do you think my suggestions my work safely for my friend ?

    1. Hi Dwayne! Sounds like a great suggestion to use a single-pole contactor to control the Aprilaire EAC and connect the 24-volt coil of the contactor and to the G terminal on the control board to power the EAC. I think this should work well. I am sorry I do not know of a replacement control board for that air handler that has an EAC or Humidifier hook up on it. You could probably use an Aprilaire A50 to control the EAC, but I am not sure the A50 relay is strong enough to support the Aprilaire 5000 electronic air filter. You might call Aprilaire customer support and ask for their suggestions. Aprilaire’s customer support number is 1-800-334-6011. I think that your idea is probably better than using the A50 relay. I hope you have a great day and Thanksgiving week! Steve

  3. My York Affinity 9C Series furnace would not start. I found one of the wires had broken off of the limit switch on the inducer blower motor. Please note that it is in fact a limit switch and not a pressure switch, and it is mounted directly on the case of the inducer blower motor. I bypassed the limit switch for now until I can get a replacement. Is this safe. The furnace seems to run through its normal cycle just fine now.

    1. Hi!
      I would think that it would be safe until you get it fixed. I would suggest that you get it fixed as soon as possible. The limit probably senses the temperature of the draft inducer. If your vent got stopped up then this could be a problem, but you would think if the vent gets stopped up that another rollout, pressure switch or limit would trip and stop the operation of the furnace. If you want me to look up the part please send me your York furnace’s model number to our email address: arnoldservice@gmail.com Hope you have a Happy New Year! Steve

  4. Working on my outside unit the fan locked up. I changed fan motor and dual capacitor. Inside the electrical there is a hard start installed aftermarket. If I put a new capacitor will I still need the hard start if line voltage is correct in?

    1. Hi Ken! The hard start is for the compressor only so if the compressor starts OK then you should not need the hard start capacitor. We sell a reasonably priced hard start capacitor on the following page: https://arnoldservice.com/product/supco-spp6-compressor-hard-start-booster-capacitor/ but as long as the compressor starts OK you will not need it. Thanks for asking the question. Steve

  5. Hi,

    My heat pump compressor randomly and infrequently quits. I flip off the main circuit breaker for a minute, turn back on and cools great again and may run ice cold for days. I never know when.

    The last time it went off, I check contactor and was at 240v, 24v across relay.
    Dual cap test good. Air filter always clean. Fan runs. New thermostat.

    I see you sell the the OEM defrost board 1087952 and thinking about RR. Since it has a few relays. My HVAC guy wants to install a new system r22 to r410a…$$$$$.

    I feel it is a infrequent bad component. Freon must be ok, cause it holds temp and will freeze you out. It’s 13 year tract unit maybe a Tempstar.

    Any thoughts on why resetting breaker restores compressor to cooling?

    Charlie Linkowich

    1. Good Morning Charlie!
      Some problems that might cause a compressor to go out where you have to reset the breaker would be if you have any loose high voltage connections. I would recommend that you turn the power off and make sure all connections are good and tight. Another problem could be that the circuit breaker could be arcing inside on the breaker’s internal contacts. If you feel the outside of the breaker after your AC has run for an hour or so and if the breaker is warm then this is a sure sign the breaker is arcing and needs to be replaced. A tight compressor that is under too much load or if the piston is getting tight can run over the RLA/FLA (Running load amps or Full load amps) and can blow the breaker if the unit is drawing too many amps. I would recommend making sure the unit is clean by cleaning with a garden hose and checking the amp draw on the compressor to see if it is within the RLA/FLA running range on the unit’s specification plate. If your compressor is tight and running over the RLA then it is either dirty, over-charged or the piston is getting tight and probably would need to be replaced soon. If your breaker and wire for your unit is undersized then this could cause the problem. Most unit’s require a 30 amp double-pole breaker and #10 wire. A weak transformer that is not producing a minimum of 24 volts AC to the contactor coil can cause contactor chatter and cause the breaker to blow. A thermostat with weak batteries can also cause this problem. I hope you can easily find and fix the problem. Steve

  6. Mr. Arnold,Have a Rheem model RAKA-024JAZ serial #5882/M1100/21908. A.C. condenser fan not running,compressor runs & sounds good until it heats up,with a Guess? I replaced the capacitor with a duel titan ,but this did not cure problem,but the $19.00 was cheap compared to the $400.00 Reids charged me a few years ago,so a extra capacitor will be good to have on hand. So i’m thinking the contactor or the condenser fan motor is the problem? What do you think sir?

    1. Hi Keith! It you are getting 220 to 245 volts AC between L1 and L2 (Power wires coming from your disconnect box) on the contactor and when the contactor is energized getting 220 to 245 volts between T1 and T2 then the contactor is OK. I would suggest that you trace down the two wires that power the fan motor and see if you are getting 220 to 245 volts AC to the fan motor when the unit is turned on. Please be careful when working with high voltage electricity. If you are getting 220 to 245 volts to the fan motor and the motor is not running then you probably need a new fan motor. Our Rheem, Ruud parts program shows that your unit uses fan motor part number: 51-23055-11 which we sell on the following page: https://arnoldservice.com/product/51-23055-11-rheem-ruud-air-conditioner-condenser-fan-motor/ I hope you can easily find and fix the problem. Steve

      1. Thank’s Steve! Checked as you suggested,good voltage on everything( including the motor when energized.Noticed the replacement motor has 6 wires to my motor with 3 black, brown, & orange??Does the replacement motor have a diagram or better (instructions for idiots)LOL! also will my new duel titan pro#25/5mfd370440 capacitor be compatible? Also since the contactor is not expensive ,could you give me the part number please and i’ll order this also as a backup .Thank’s again Brother!

      2. Hi! All motors come with a wiring diagram on the label of the motor. Motors do not come with instructions but we have a good video on this subject on the following page: https://arnoldservice.com/air-conditioner-condenser-fan-replacement-video/ I searched our database and did not see which motor you purchased from us? I see where you purchased the 25/5 mfd Titan Pro Capacitor, but not a motor. If the motor that you purchased uses a 5 MFD capacitor then the 25/5 MFD Titan Pro Capacitor would work well. If you would like for me to look up the contactor part number please send me your units model number and if you have a Bryant Carrier unit I will need the product number. Please send this information to our email address: arnoldservice@gmail.com. It would be best to communicate using our email. I hope you have a great day! Steve

  7. An electrician friend said the capacitor on my heat pump was bad and needed to be replaced. He got one and last night at 15 degrees when I turned it on, it blew the circuit breaker. Now he’s saying it’s the compressor. I think he’s fishing b/c he never came back to check anything. I’m very suspicious of his hit & miss diagnosis and don’t want to spend a fortune replacing parts. I’m also on a fixed income due to a disability.

    1. So sorry to hear that you heat pump is not working. If it is staying at 20 degrees or below outside for long periods of time I would suggest turning your system to emergency heat. You electrician friend could be right. I have seen compressors fail shortly after replacing a bad capacitor. Your electrician could have done a test to see if the compressor is actually bad. We discuss this in a post on the following page: https://arnoldservice.com/problem-i-installed-the-new-capacitor-and-the-boost-cap-i-received-now-the-outdoor-fan-will-start-briefly-but-the-compressor-does-not-the-power-management-box-on-the-side-of-the-house-shuts-off-pow/ I would suggest the you get another opinion by a licensed HVAC company if you are skeptical of the electrician. Most of the time when the breaker blows on heat pump start up it is the compressor grounding out and you will need a new compressor or a new heat pump system. I hope you can get it fixed soon! Steve

  8. I ordered 1 bryant/carrier 2 wire piolt burner #LH33JZ053
    with expidited shipping (38.00) dollars pid with PayPal
    on sunday 11-26-2017.
    please confirm order and let me know when i shuld receive

    fred lange
    46 jensen rd
    sayreville NJ 08872

    phone # 732 718 4242

    1. Hi Mr. Lange!
      Sorry you did not get my email earlier this morning. Here is a copy of the email I wrote to you about 8 AM this morning:
      Dear Mr. Lange!
      I am terribly sorry, but I called both of my suppliers so I could pick up the two wire pilot burner and they do not have it in stock. I have canceled your order and refunded your PayPal account in full. I hope you can find it on another site. I copied the transaction details which show the refund below. So very sorry!
      Steve Arnold, President

  9. Having problem with my Carrier Furnace, Draft inducer motor not working, Tape the blower door safety switch shut (if equipped) and set your thermostat so it is calling for heat. Use a volt meter set to “Volts AC” and test between terminals W (usually white wire) and C (Com) getting, 25.6 volts between these two terminals. AC between the R (red) and C (com) getting, 26.8. Check the fuse it looks good.

    I start the furnace and the Fan blower starts but the draft inducer does not and continue to blow cool air no fire, LED blink continous on and off.
    Now what do i need to do next.

    1. Hi! The voltages that you tested between W and C and R and C are normal when the furnace is calling for heat. It sounds like you either have a control board problem where the relay on the control board is not sending voltage to the draft inducer or you have a draft inducer problem. I would suggest checking the voltage that goes to the draft inducer. If you are getting 110 volts to the inducer motor and it is not working then your have a draft inducer motor problem. If you aren’t getting voltage to the draft inducer then you need a control board. It is normal for the furnace fan to run for a couple of minutes when the furnace is powered up from the power switch. If you would like for me to look up part then please send your furnace product number to our arnoldservice@gmail.com email address and I will be glad to look up parts. I hope you can easily find and fix the problem. Steve

      1. Steve,
        I’m only getting 25 volts AC, the wires that connected to the draft inducer .
        My PC board, P/N 1012-940-J HK42FZ009.

        Rudy del Rosario

      2. Hi! If you are only getting 24 volts to the draft inducer when the thermostat is calling for heat then you probably need a new control board. Please make sure that you are getting 24 to 28 Volts AC between the C (com) and W terminals on the control board when your thermostat is calling for heat. The HK42FZ009 control board has been replaced by the 325878-751 conversion kit control board that we sell on the following page: https://arnoldservice.com/product/325878-751-bryant-carrier-furnace-control-circuit-board-conversion-kit/ If you aren’t getting voltage to the draft inducer then more than likely the control board is at fault. I hope you can easily find and fix the problem. Steve

      3. Steve,
        Draft Inducer motor is this 110 volts , DC or AC.

      4. The draft inducer on most furnaces are powered by AC voltage. If you have a high efficiency furnace with an ECM draft inducer then it runs on DC. ECM motors are hard to troubleshoot and usually require special equipment for testing the motor. I hope you can easily find and fix your problem. Steve

  10. my rheem 3 ton gaspack will not ignite have replaced gas valve and ignitor getting spark to manifold when unit calls for heat I can light manually unit lights and runs until unit gets to set temperature .wnen thermostat calls for heat it sparks will not ignite can light manually

    1. Hi Mr. Creasy! Sorry to hear you are having trouble with your Rheem gaspack. Since the unit works correctly when you light it manually, then this sounds like to me it would be an issue with the control board not sending power to the PV (Pilot Valve) on you gas valve to light the pilot. The control that sends the power to the gas valve whether it be a control board or another control then this is probably your problem. Just to make sure I would suggest that you check all safety controls like the limit, rollouts and pressure switch to make sure they are closed and you can eliminate these safety controls as the problem. If you need me to look up parts please send your furnace’s model number and serial number to our arnoldservice@gmail.com email address and I will be glad to look up parts. I hope you can easily find and fix the problem. Steve

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