Carrier Thermostat Clock not keeping time

When you took it off the wall, did the clock stop completely? If not, then (assuming it was off the wall long enough for any energy storing capacitors to drain) it must have a battery.

Yes, the entire LCD went blank.

Probably the clock circuit itself is controlled by a quartz oscillator, so it should be quite accurate.

But perhaps its power supply is marginal. If so, it might be easily repairable (e.g. new diodes or capacitors).

Or perhaps the AC supply itself is marginal. Is there any chance of a loose connection anywhere in the system?

Beyond that, it sounds like a replacement might be necessary.

Any chance it's still under warranty? This kind of stuff should last longer than 3 years.

Some digital thermostats can be removed from the wall without making the batteries visible - they remain within the unit you're holding in your hand. You might need to open a faceplate or something. Where is your instruction manual? Or, go to

Never heard of a programmable thermostat that doesn't have a battery. Normally they are powered by AC but the battery is to remember the program when the AC power goes off. A low battery could affect the clock.

Still doesn't prove there is no battery if the battery is dead.

A low battery can affect the clock by stopping it or having it reset to

Sounds like this is a defective thermostat

Repair questoins might be posted at sci.electronics.repair , but if it turns out that it is broken, that is, a new battery doesn't help, I think Carrier might give you a new one whether the guarantee is still in effect or not. I have no experience with this, but this is the not the kind of problem caused by abuse, or damage, or your kids, but something inside went bad not because of any of that.

How long has it been broken?

The clock ain't working, so how would he know?

Had the same problem. When I pulled it out I did not see any battery compartment