Duo Therm Heat Pump weirded out

Hello Doug, I did replace the AC unit about a year and a half ago (it's the new style Duo Therm), but they sold me a control unit (the electronic box that fits up in the new AC) that was supposedly designed to make the new AC work with the old five button CCC thermostat. I think I was concerned that there was no way I could run a new thermostat wire up to the unit, as it runs through the wall, and somehow I understood a new thermostat needed a different wire. I really don't remember why I stayed with the old thermo. It has worked great for a year and a half until this morning. My control unit is a 3109226.005. So I'll try the thermostat reset. Otherwise, you think its the control unit., is that right? I wasn't sure whether it would be the thermostat or the control unit. Thank you very much for the info. Duo Therm is impossible to get tech support from.

As usual Doug knows his stuff. Since you have a 5 button Tstat and it's defaulted to heat it's a old style unit (like mine) and the control board is 3109229.009.

I would try a Tstat reset although it sounds like a control board:
SYSTEM RESET
a. Turn the ON/OFF switch to (OFF) position.
b. Simultaneously depress and hold the MODE and ZONE
push-buttons while turning the ON/OFF switch to (ON).
FF should appear in the LCD display until the MODE
and ZONE push-buttons are released signalling proper
communication between the Tstat and upper control
board.
If you do not get FF then I would try cleaning the contacts on the phone plugs that connect the Tstat and control board.



$125 on Ebay.

howardwheeler wrote:
I have a less than two year old Duo Therm Heat Pump that has suddenly started having the compressor run anytime 120 volts is to the unit. Only if I shut off the breaker will the compressor stop running. The fan doesn't run unless I put it in non-automatic mode. I have a five button CCC thermostat. I did lose 12 volt power last night, but the ac worked fine after that. 12 volts are back working now, but the AC compressor runs all the time. It is apparently stuck on heat pump, because when I put the fan on run hot air comes out. It's under warranty but I can't get service to look at it yet and we are using the unit. Any ideas?

Your Compressor Relay on the Upper control board is stuck CLOSED. This is not a replaceable part(the relay). Replace the 5 button upper control board. Your timeline does not make sense. The 5 button has not been used in almost 5 years. Do you mean the Upper HP was replaced less than 2 years ago? If so, then the upper board was not replaced when they changed out the unit(you do not unless it was bad). Doug