I need to change a carrier (Y841A 1647 HH07AT215 class 2) thermostat to a honeywell (TH4210D - 2 heat/1cool heat pump). I can't find the wiring diagram for the carrier thermostat. I need to identify what terminal (and color wire) and function on the carrier corresponds to the honeywell.

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Originally Posted by thermostatMA

I need to change a carrier (Y841A 1647 HH07AT215 class 2) thermostat to a honeywell (TH4210D - 2 heat/1cool heat pump). I can't find the wiring diagram for the carrier thermostat. I need to identify what terminal (and color wire) and function on the carrier corresponds to the honeywell.

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Look at this. Look at BDP or Carrier for help with wire. Do not worry about color use the letter or number where the old wire is placed on the old thermostat to go to the new..

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Originally Posted by hvac1000

Look at this. Look at BDP or Carrier for help with wire. Do not worry about color use the letter or number where the old wire is placed on the old thermostat to go to the new..

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Thank you. Another question: will the carrier terminals (letter where wire is attached) match the honeywell lettering? For example, the carrier lettering is E G Y O R W2 C whereas the honeywell lettering is E Aux Y G O L R B C. So what letter corresponds to what? Is the following correct? E-E G-G Y-Y O-O L- leave blank R-R W2-Aux C-C B-leave blank.

That is why I posted the heat pump change over wiring diagram. Some letters/colors might use a different designation/letter/color.

The only true way to make sure all is absolutely correct is to trace all the wires down,see where they go, and pick the correct post to land the wire on. This is what professionals do many times when there is a question with thermostat wiring. I supplied you the cheat sheet to help you prevent having to do that.