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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Lennox 21j7101 thermostat that I'm changing out for

Customer Question

I have a Lennox 21j7101 thermostat that I'm changing out for a Honeywell RTH3100c. Somebody ripped old thermostat wiring labels off. What colors do I use on new thermostat? I have connected but AC won't come on. Only heat running.
Submitted: 1 year ago.
Category: HVAC
Expert:  Gaztech replied 1 year ago.
Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue.If my initial response doesn’t answer your question then let me know and we can continue our conversation.NOTE: I can only get paid for assisting you if you click FINISHED and RATE ANSWER after you are satisfied with answer.Are you ready?
Customer: replied 1 year ago.
Yes
Expert:  Gaztech replied 1 year ago.
What are your colors
Customer: replied 1 year ago.
White, brown, blue, yellow, orange, red, green, black
Expert:  Gaztech replied 1 year ago.
White-W1, brown-W2, blue could be Y2 it depends if your heat pump has 2 stage compressor, yellow-Y, orange-O, red-R, green-G, black should be C if it was done to standards
Customer: replied 1 year ago.
I don't have a W1 or W2 on new thermostat. I have an E and an Aux
Customer: replied 1 year ago.
I have an E, Aux, Y, G, O, L, R, B, C. On new thermostat terminals.
Expert:  Gaztech replied 1 year ago.
Refer to page 12 of manual and read item 3 and 4
Customer: replied 1 year ago.
Yes have read them, was just seeing if I could get some better direction on wiring
Expert:  Gaztech replied 1 year ago.
White and brown-aux with jumper between E/aux, yellow-Y, orange-O, red-R,green-G, black- C, Blue?( to find the answer you will need to go in the furnace and see what wires are on what terminals..
Expert:  Gaztech replied 1 year ago.
What are the letters on the old t-stat?
Customer: replied 1 year ago.
Y1, G, O, E, W1, C, T, L, R.
Expert:  Gaztech replied 1 year ago.
Blue could be for L witch is error signal from heat pump, does not need to be hooked up for system to work. NOW I would go in the furnace and see what wires are on what terminals..take a clear picture of furnace wiring and send it to my***@******.***
Customer: replied 1 year ago.
OK I sent it.
Expert:  Gaztech replied 1 year ago.
ok
Expert:  Gaztech replied 1 year ago.
Can you take a another clear picture with the letters to each terminal, you may need to clean the area to read it properly
Expert:  Gaztech replied 1 year ago.
Did you solve the problem?

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