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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Bryant forced-air/heating-AC (gas) heating/cooling

Customer Question

I have a Bryant forced-air/heating-AC (gas) heating/cooling unit, and I've got a honeywell CT87N4450 thermostat.
The A/C isn't working, and I'm not sure if this unit is hooked up properly, and the heat works just fine.
There are three wires coming out of the harness to sire into the thermostat:
and they all seem to be wired to the right places. There is also a switch on the thermostat that has a "E" and "F" position, and currently its setting is "F".
Is this wired up correctly?
Submitted: 2 years ago.
Category: HVAC
Expert:  Tim H. replied 2 years ago.
Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.I see no one has responded to your question. Did you still need assistance with this? Is this a new thermostat you installed or was this already in place?
Customer: replied 2 years ago.
I still need assistance with this. This thermostat was (I believe) new, and installed prior to my moving in. The previous thermostat was one that could be controlled via internet, etc. This one, is the Honeywell mentioned in my previous post.I've viewed a few videos, and they show 4 wires being wired into combination heating/cooling systems, while mine has three. Hence my question. Thanks.
Expert:  Tim H. replied 2 years ago.
Yes, for AC to work, you need a wire from furnace to Y terminal
Customer: replied 2 years ago.
Ok. How do you propose I proceed? Is ther a way to check directly from the furnace to see if there are sufficient wires in the harness?
Expert:  Tim H. replied 2 years ago.
You would need a total of 4 wires in the thermostat "bundle". If you don't have that, you would need to run a new thermostat wire bundle OR you can give up the fan wire (green) and use this for AC function.