I replaced a non programmable t-stat with a Honeywell 6000 programmable t-stat on a Carrier Package Heat Pump. I do not remember the brand of the first t-stat. I checked fan only, heat, and cool modes to make sure it was set up correctly. All was well. Later, I got a call from the customer saying it won't turn off. If it is set to 70 degrees in heating it continues to heat way past that setting. When I switch it to off, the system continues to heat, fan included. The programmable won't shut off in heat mode only. I have to physically remove the stat from the sub base to disconnect power. When in cooling it operates normally. I switched thermostats, another 6000, a 4000, and a Source 1 non programmable. I switched t-stat wire directly at the unit when testing different stats. The non programmable stat will shut off when switched to "off", but still continues to heat when left to operate off of temperature. I spoke with Honeywell and they said it's a wiring issue with the unit, but the unit operated normally before I changed t-stats. I've triple checked wire connections and terminal voltage. All factory wiring is still in place, and matched the wiring diagram. The reversing valve solenoid is engaging when power is applied, and as I mentioned all modes are operational. I traced all wiring at unit to the factory wiring diagram in the unit. I confirmed 24v to relays, boards, solenoids, and controls. When I spoke with the Honeywell tech support they confirmed all functions, modes, and wiring at the thermostat to be correct. He even said he had not encountered this before. I am very puzzled at how the unit operated fine with the original non programmable thermostat, and now this problem arises when I change t-stats.
The Carrier model # 50HJQ006---321. Serial # 0506G40519. I would like to know what brand and style of t-stat to use for this unit, and why it doesn't operate with others. Thanks.