Thermostat trouble

[jason1200]

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. 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. I switched thermostats, another 6000, a 4000, and a Source 1 non programmable. 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.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.

[tudorice]

Check ur wiring to the thermostat again, if thats all ok, it could be a faulty sensor or even thermostat.

[jason1200]

p.s.
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 switched t-stat wire directly at the unit when testing different stats. 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. The non programmable stat will shut off when switched to "off", but still continues to heat when left to operate off of temperature.

[jason1200]

I checked the stat wiring several times. I've tried 2 Honeywell 6000's, a Honeywell 4000, and a Source 1 non programmable. Which sensor might be faulty?

[Brian_UK]

I know that you have checked the wiring but 'have you checked the wiring'? All links fitted or removed as required.

Can't track your full model number just referring to this Carrier manual...
See Fig 37
http://eto.carrier.com/litterature/iom/50HJQ_ISS.pdf

and Honeywell
http://www.alpinehomeair.com/related/TH6000%20Series%20Installation%20Guide.pdf

[jason1200]

I installed my own 'known to be good' t-stat wire at the rooftop unit while swapping each t-stat. 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. NOTHING AT THE UNIT HAS CHANGED. Please help cure my insanity.

[hvacrmedic]

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. 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. I switched thermostats, another 6000, a 4000, and a Source 1 non programmable. 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.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.

The 50HJQ uses a standard two-stage heat two-stage cool thermostat. Do not use a heat pump thermostat, or, if the t-stat is configurable for heat pump or non-heat pump, then set it to non-heat pump mode. In heating mode the compressor will be energized by W1 and the strip heat by W2. The unit's CB handles reversing valve switching.

HTH.

[Sledge]

The electronic thermostats utilize solid state circuitry to switch the load on and off. The problem is that due to poor design and cost saving measures, they do not provide a positive shut off. Sometimes the current flow through the transistors will cause the transistor to stay on...an electronic issue. This happens a lot, when the electronic circuit on the thermostat is switching a signal to an electronic circuit in the unit.
To solve this problem, install relays inside of the unit. One relay for fan, one for cool, one for heat etc. Wire it so that the thermostat will control the relay, and the relay contacts will send the signal to the unit.

[nic monaghan]

check all known contactors on the unit. perhaps fault there