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Ask airheatman Your Own Question
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8326
Experience:  Furnace, A/C and heat pump specialist.
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Intermittently, once every 2-3 months, my central a/c won't

Customer Question

Intermittently, once every 2-3 months, my central a/c won't shut off. It's a two zone system and has happened on both thermostats which are different brands. Almost always, it's when we manually adjust the temperature. If I had to guess, it has something
to do with how long it takes the handler to shut off (which is about 30 seconds after the click) and when we make the manual adjustment or when the temperature is already below the set temperature but the thermostat hasn't shut off yet. Either way, the a/c
doesn't shut off and the temperature can get very cold unless I lower the thermostat past the current temperature and wait for the click, give it a minute (literally 60 seconds), and then raise the temperature again until I here it click. Then the a/c will
shut off. I get nervous that one day this will occur when we are not home and the temperature drops low enough to freeze up the system. The whole system is less than 7 years old.
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.
If your unit is still running and you lower the temp and hear it click, it sounds as though the thermostat is not recognizing it has reached the setpoint.I would go ahead and replace that thermostat as the sensor is most likely out of calibration.
Customer: replied 2 years ago.
Do you have a preferred thermostat that you recommend?
Expert:  airheatman replied 2 years ago.
Do you want programmable?
Expert:  airheatman replied 2 years ago.
Honeywell 5000 series for non programmable and Honeywell 6000 series for programmable