Ct100 plus - temperature not reacting to cooling room?

[talz13]

I’ve got a new ct100 plus that I installed back in October, running @RBoy 's enhanced thermostat DH version v04.00.00 . It’s been working great, up until A/C season started. There’s nothing wrong with it responding to commands, but it seems that the temperature reading does not necessarily reflect when the room is cooling down, causing the A/C to keep running for extended periods of time.

Tonight, we came home around 7:15, the house was 77F, and the thermostat gets set to 76F on returning. WIthin the first ~10 minutes, the thermostat is reading 76.5F. Two hours later, the A/C is still running, and the living room (next room from the thermostat) is down to 74F, the master bedroom is down to 72.5F, and the thermostat is still reading 76.5F.

So I know the air is cooling around the house, well past the cool setpoint, but it’s like the thermostat doesn’t want to get the drift and recognize that fact.

Any ideas? (also, it is powered by C wire)

[ero4444 (Eric)]

just a guess, maybe you haven’t operated it in a high-demand cooling mode until now. Maybe there is a heat source on the tstat location, acting in summer, that does not act in winter. Possibly even in the wall - you could insulate the hole.

Reminds me of the time that I got frozen on an intermittent basis in winter in a datacenter office, it seemed mysterious. In that case, a laser printer vent was hitting the tstat from 6-7 feet away and was sorta channeled to it, but only when printing - sneaky.

The tstat could be failing or miswired for cooling, or the HVAC controller could be failing. When my furnace was troubled, it would run-on for hours, even though actual heat was correctly cycling and on average, it was able to maintain temperature. Looking at the controller, it did flash a code, in my case 5-fast-blinks, indicating “flame without ignition”, which was actually untrue, but the run-on condition is both a fail-safe response and a notification to “look at the HVAC, dummy”.

I finally replaced the controller after 2-3 years when it ran for 8+ hours straight. Saving that fan energy.