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I'm replacing an old model Honeywell thermostat with a new…

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I'm replacing an old...

I'm replacing an old model Honeywell thermostat with a new T3 programmable thermostat. The old thermostat was connected with four wire; green, red and two whites. There is a fifth (unused) red wire in in the bundle. I'm confident about the locations of the red, green and one of the white wires on the new thermostat. The other white wire was connected to a terminal that was either orange or yellow. Should the second white wire be connected to the orange or yellow terminal. Does the second red wire that was previously unconnected have a function?

Contractor's Assistant: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?

We had a technician check out the furnace when the problem first arose about 4 weeks ago. He said the furnace was fine. Furnace stopped working again so assumed but not absolutely certain the problem is the thermostat.

Contractor's Assistant: Do you plan on doing the work yourself?

Replacement of the thermostat appeared to be relatively simple and I have a fair amount of experience with electricity and mechanics so I started on the job myself.

Contractor's Assistant: Anything else we should know to help you best?

Can't think of anything else. Ask if you have questions.

Submitted: 9 months ago.Category: HVAC
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Answered in 4 minutes by:
12/6/2017
HVAC Technician: Rick, HVAC Supervisor replied 9 months ago
Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 24,848
Experience: 40+ yrs. experience as a licensed oil & gas technician.
Verified

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. First I’ll need some more info so I have a more complete picture of your situation.

Did you label each white wire? Thermostat terminal designations are not color referenced although they can correspond with the first letter of a wire color. Typically the 4th terminal of a 4 wire heat/AC config would be the Y terminal.

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