It sounds like you have an ambient temperature sensor that is out. There are two for this system or the controller is going out. I would remove the sensors to check the electrical connections for corrosion caused by moisture first. Here are the sensor locations and the air conditioner wiring diagrams so you can see how the system works. You can also have the HVAC system scanned at the shop for a trouble codes it should cost about $70.00.
Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
Cheers, Ken
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Thursday, September 20th, 2018 AT 3:41 PM