My air conditioned runs for about an hour and then it shuts off while the fan is running for about 5-10 minutes and then it comes back on for 5-10 minutes...if it is the thermostat switch, how can I fix it?
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Re: Problem with the thermostat?
I am not sure what kind of air conditioner this is, but it is possible that it is low on refrigerant. This would cause the line to begin to freeze. When the line starts to frost over the anti freeze protection will shut the compressor off until the frost goes away. Then the compressor will turn back on and begin the same cycle until the refrigerant levels are corrected.
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Multiple problems. Eliminate thermostat first. Remove face from wall and turn on breaker. If fan still runs you have a bad board or bad relay. If fan outside is running compressor should be too. These operate on same contactor. Verify you are getting 24 volts to coil side of contactor. If odf stops working and contactor remains pulled in you have a bad motor. If odf motor stops working the compressor will shut off due to overheating.
Hi David. when the air conditioning is energised by the thermostat it should automaticly bump up to high fan speed, if it has been running for a while it ciould be freezing up the evaporator and causing a restricted air flow to come out. you may need to shut the cooling mode off and just leave the fan running for a few hours. hope this helps
your thermostat could be wired in to a energy recovery venilator which will bring the unit on for a certain amount of time every hour some thermostats have recirculate mode which will do the same thing to help filter the air
Is this a new hvac system? A new furnace can work differently than your old one. Does it shut off after a minute or two or continue to run? If it continues to run then call that professional back and let him fix it. If it shuts down after a minute or two then it is a feature of the new thermostat to squeeze all of the cool it can from the a/c coil and ductwork.Some of them have settings that you can adjust for blower delay on and off, read the manual that came with the t-stat and see if it does.
There is a built in delay on all HVAC systems to evacuate conditioned air (hot or cold) from the ducts -- it's just more efficient that way... but if it's staying on for more that 4-5 minutes at most then there may be a problem with the fan relay... or possibly a limit switch.
Does it run longer at a higher temperature say 20° or 21°and what's the outdoor temperature?
Try to run system at a higher temperature, to see if you still have the same problem, if you don't then you may have a low pressure switch opening and shutting the compressor down. If this is the case the outdoor temperature may be too low, dirty filter or indoor coil, fan speed too low or low on refrigerant.
If not then it could be run capacitor, loose wire or thermostat.
Is the unit ducted with a wall mount thermostat? If so, then I would say that you need to check the thermostat. Remove the face plate from the thermostat, there should be 6 or 7 wires, depending on the model. With the thermostat set to high/cool, check for power at the yellow wire and the blue wire. Yellow is the compressor terminal and blue is the high fan. If you have no power at the blue terminal, then you have a bad thermostat. If there is power there, then you need to access the control unit in the air conditioner (remove inner shroud). Check for power at the blue wire at the control unit. If there is power, then you have a bad control unit. The unit is shutting down because it is freezing up in the low fan speed position. You can use a jumper wire on the thermostat to go from the +12 terminal (red wire) to the Hi Fan terminal (blue wire) and also the fan terminal (Either tan or orange, depending on the model). If the fan comes on, then you have a bad thermostat. If not, then you have a bad control unit or the high speed in the fan motor is out.
Most thermostats have a setting for the fan called, "manual". That keeps the fan on continuously. The electronic thermostats can fail in a "fan on" condition. That would require a new thermostat. I also saw one air conditioner with a fan relay welded "on" by electrical surge. That would require a new relay.