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Problem: Air Conditioning outdoor condensing unit or heat pump unit will not shut off.

Happy AC

Problem: My air Conditioning outdoor condensing unit or heat pump unit will not shut off. It continues to run no matter what you do. The only way you can get the outdoor unit to shut off is turn off the breaker or pull the outdoor disconnect.

Solution: You probably need to purchase a new contactor. Contactor’s Purpose: The contactor has a 24 volt relay, when this 24 volt relay is energized from the thermostat, a call for cooling, the contacts on the contactor close, making a high voltage (220-240) connection to your compressor and outdoor fan, causing the outdoor unit to come on. There are several types of contactors that we sell. Please click here to see the contactors we sell. *Please make sure your electrical power is off before attempting to remove or work on air conditioning equipment. Pull the outdoor disconnect or turn of the indoor breaker that controls the air conditioner. Turn the furnace off or thermostat off so no low voltage is going through the low voltage wiring. When deciding on what contactor to order you would need to know if you have a single pole or double pole contactor and the FLA (Full Load Amp) rating on the contactor. If you need advice or help on which contactor to order please email us at: support@arnoldservice.com  Please send us a picture or your air conditioner’s or heat pump’s contactor or the unit’s model number. A picture of the specs on the contactor would help lots! Sometimes when the contactor fails the outdoor condensing unit will not come on at all. Dirt or insects (I see ants many times) can get in between the contact points while the contactor is off, and cause the air conditioner not to come on at all. When the contactor is stuck in the “On” position (contacts welded together), Ice will form on the indoor evaporator coil and all the way out to the outdoor unit. I have seen 1 or 2 inches of ice form on the line set and outdoor unit compressor. You will not get hardly any air flow through your duct work when this happens because the indoor evaporator coil has become a complete block of ice. If this is your problem then your contactor points could be stuck, welded together causing the outdoor unit to run continuously. Many times when ants or insects get between the contactor points, the outdoor unit will run (burns the insect out), but because of the uneven wear (arcing) in the contact points the contactor will soon fail. Arcing causes a tremendous heat build up and pitting of the contact points. If you are in an area of the country where insects are prominent in and around air conditioners, then I would suggest you turn off the power to your unit, blow your contactor out with compressed air and check to make sure you do not have any insects in between the contactor points at the beginning of each cooling season. You might want to keep a spare contactor on hand? I would like to suggest that you purchase a contactor that has a cover over the contacts. We sell these on our contactors page. Another problem that can cause contactors to fail quick is if the contactor is not getting enough low voltage to the coil. Please make sure the contactor is getting at least 24 volts AC to the coil. If the contactor is not getting the needed 24 volts then this can cause the contacts to chatter and burn up quick! I have seen weak transformers, weak batteries in a thermostat and shorted thermostat wires cause this problem. If you hear your contactor chatter then please find out what is causing the low voltage problem soon, because this chatter will cause a contactor to fail soon.  If your contactor looks like the single pole contactor below, with burnt or pitted contacts then you definitely need a new contactor. The picture below is of a single pole contactor out of a Rheem air conditioner. The blue and yellow wires (near the bottom of the picture) are the low voltage wires that come from the thermostat. The red and black wires on the right side are the high voltage wires coming from the disconnect box from the house. The four wires on the left side connect to the compressor and fan to make them come on when the contactor is energized by the low voltage wires (blue & yellow) coming from the thermostat. Solution: You need to solve this problem by purchasing a new contactor. We sell various contactors on the following page: Please click here if you might be interested in purchasing a new contactor.  Please watch the Youtube video below on How to Change a Contactor if you want:

Air Conditioning and Heat Pump Troubleshooting

3 thoughts on “Problem: Air Conditioning outdoor condensing unit or heat pump unit will not shut off.

  1. I have a Bryant evolution air conditioner with heat pump. My air conditioner will work normally for a few day to a few weeks then all of a sudden it will try shut down and can’t. I must build up pressure somewhere and release it over and over again and will not shut down. Every minute or so you can hear the pressure relief valve go off. I will have to go out side and pull the disconnect to get it so shut down. If I pull the thermostat inside it still stays running and doing the pressure relief valve thing. I hit system off and it won’t shut down it just keeps cooling. During the heating season it works just fine. I was told it could be a reversing valve. Does a reversing valve fail intermittently. Could this be a failed contractor? Is there a bad relay on the motherboard? Could this be shorted wiring keeping the contractor pulled in? It is an intermittent problem and doesn’t effect the heating cycle.

    1. Hi Mr. Swedbert!
      Sorry to hear that you are having trouble with your Bryant Evolution heat pump. I am sorry I do not know anything about the high tech Bryant Evolution heat pumps. I am sorry, I have not done any service work since 2005. I do know that reversing valves are energized in the cooling mode all the time on most heat pumps other than Rheem Ruud where the reversing valve solenoid is energized in heating mode. The reversing valve solenoids are most of the time powered by 24 volts. If the solenoid is getting low voltage (under 24 volts) then it would cut off like you described. This could be attributed to several problems like a loose thermostat wire, weak thermostat batteries, weak relay on the thermostat, a weak low voltgage transformer or the control board, I would suggest that you try to trace the reversing valve solenoid wires down an see if the voltage is at or above 24 volts. If it is below 24 volts then you will need to see why. Sorry that I can not be much help. Bryant offers classes to their dealers on the evolution heat pump so you will probably need to call an authorized Bryant dealer to come and find what the problem is. I hope you have a great day and weekend!
      Steve

  2. I hope this will help you troubleshoot and repair your air conditioner or heat pump. I will be glad to try and answer your questions. Please leave a comment if you have any questions or more advice. Thanks so much for your interest and support in our site! Hope you have a blessed day! Steve

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