A/C Continues to Run below Setpoint?

Question

I have a Honeywell RTH230B thermostat that should be controlling to ~73 degF in the house, but the A/C continues to run and can get into the lower 60's if I don't turn it off before it gets that low. The display does not show the symbol that it's commanding the A/C on when it's below the setpoint, but it's still not turning off! Is this simply a thermostat problem, or could it be a sign of something wrong with the A/C unit itself?

Answer 1

It is likely just the thermostat (most common failure with heating and cooling problems) and as this is the cheapest and easiest to change component in the system I would suggest starting here with a DIY fix.

Answer 2

me personally, would listen to lamont. it may be the t stat, but stuck contactors arnt uncommon either. do what he says first, dont touch anything in the service bay though.

your ac will get your house to the low 60's? wow, that has to be at night.

Answer 3

Shut off the power. pull the electrical cover on the condensing unit outside There is a contactor on the condensing unit outside , Restore power start A/C, you should see the contactor click and pull in.... Have someone turn up the temp while you stand near it if it stays running it could be a welded set of contacts. (May need a new contactor) If it pulls in but doesn't release T-stat is bad.

Answer 4

That most definitely sounds like a thermostat problem, not a problem with the AC unit. If you are looking for a cost efficient fix, I would recommend buying a new thermostat and installing it yourself. It's fairly simple to do.

Answer 5

I don't have the manual for your model thermostat, but if it is a multistage thermostat, you may just have a programming problem. I would start there first.