Home Thermostat keeps resetting

[Russ Filtz]

It's 90+ here! I've re-done all the program temps to 68 AND set the "hold" temp to 68 also. The AC, when it does kick on, seems to only run for a few minutes and then kicks itself out of the hold temp and programming and resets the temp to 85!

For awhile it seemed to also show the inside temp as 53! It was more like the 85 it was trying to hold to. Had to reset the hold temp to 50 and it kicked on for a short while again. Then started showing a more normal temp of 71-72, but I'd say it was really more like 80. Still kicking out to 85 which naturally shuts the AC down. Not good.

No ice on the outside unit's hose which usually means low freon. Can't see the inside evap if it's iced up or not. I'd say it probably is with these weird readings?

Too much freon? Something else going on?

[Scott Donley]

If your thermostat has batteries, change them.

[Mike Henderson]

Batteries or change the thermostat.

Mike

[John K Jordan]

It's 90+ here! I've re-done all the program temps to 68 AND set the "hold" temp to 68 also. The AC, when it does kick on, seems to only run for a few minutes and then kicks itself out of the hold temp and programming and resets the temp to 85!
For awhile it seemed to also show the inside temp as 53! It was more like the 85 it was trying to hold to. Had to reset the hold temp to 50 and it kicked on for a short while again. Then started showing a more normal temp of 71-72, but I'd say it was really more like 80. Still kicking out to 85 which naturally shuts the AC down. Not good.
No ice on the outside unit's hose which usually means low freon. Can't see the inside evap if it's iced up or not. I'd say it probably is with these weird readings?
Too much freon? Something else going on?

I would first make sure all the electrical connections are solid both at the thermostat and inside the unit. To test whether there is problem with the thermostat or the air conditioning unit I might temporarily substitute a cheap "dumb" thermostat for the programmable one.

JKJ

[Matt Meiser]

Batteries or change the thermostat.

Mike

This. Thermostats are so cheap these days its not worth dinking around with.

[Russ Filtz]

If your thermostat has batteries, change them.

Thanks, changed the batteries, but still acting the same. Old batteries were a bit corroded but not too bad. I'll try the cheap thermostat next.

[Stephen Tashiro]

Thanks, changed the batteries, but still acting the same. Old batteries were a bit corroded but not too bad. I'll try the cheap thermostat next.

You have to read the set-up directions for thermostats carefully. They may involve more than programming temperatures. For example, they may have special set-up procedure that the installer is supposed to do to set whether the cooling unit is "one stage" or "two stage" or pick its type from list of several types, that are only described by numbers on the thermostat, but explained in the manual that comes with it. If the batteries are changed or go low then thermostat may loose its memory of the appropriate set up.

Typically, it won't be obvious how to get to the set-up menu for a thermostat. It will involve pressing some combination of buttons that are used for other purposes.

A thermostat that is set-up wrong may appear to turn the AC on and off at appropriate times, but it won't be telling the equipment to do the correct things.

---and some cheap thermostats aren't capable of handling all types of AC units.

[Russ Filtz]

You have to read the set-up directions for thermostats carefully. They may involve more than programming temperatures. For example, they may have special set-up procedure that the installer is supposed to do to set whether the cooling unit is "one stage" or "two stage" or pick its type from list of several types, that are only described by numbers on the thermostat, but explained in the manual that comes with it. If the batteries are changed or go low then thermostat may loose its memory of the appropriate set up.

Typically, it won't be obvious how to get to the set-up menu for a thermostat. It will involve pressing some combination of buttons that are used for other purposes.

A thermostat that is set-up wrong may appear to turn the AC on and off at appropriate times, but it won't be telling the equipment to do the correct things.

---and some cheap thermostats aren't capable of handling all types of AC units.


I replaced it with a Honeywell programmable. Pretty much copied the wire colors over, set the program, and it kicked on! Had to leave, so not sure if it kicked off too soon like before. We'll see.

[Gordon Eyre]

My furnace/AC kept cycling on and off inspite of the fact that it had not reached the set temperature. I tried lots of things until I finally gave up and bought a Nest thermostat. Yes it was pricy but my gas company gave me a $100 rebate so it wasn't that bad. Love the new thermostat and it stopped the on/off cycling and saves me money to boot. Because I have two furnaces and two air conditioners I am going to buy a second Nest thermostat.

[Mike Henderson]

I replaced it with a Honeywell programmable. Pretty much copied the wire colors over, set the program, and it kicked on! Had to leave, so not sure if it kicked off too soon like before. We'll see.

Let us know how it works out.

Mike

[Russ Filtz]

Let us know how it works out.

Mike

So far still running fine. AC can't seem to keep up though in the high heat. Can't get it below 72

[John K Jordan]

So far still running fine. AC can't seem to keep up though in the high heat. Can't get it below 72

72, yikes, I'd freeze! We set ours to 78 or 79, 68 in the winter. Of course, with the farm we spend a lot of time outside so coming in feels like a fridge or furnace, depending on the season. Pushing 90 here today.

JKJ