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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 gas funace with ac, I have a 5 wire system.

Customer Question

Hello, I have a gas funace with ac, I have a 5 wire system. right now the circuit board has been diagnosed to be bad. reason being, when the ac kicks on, the fan kicks off. I tried to set the tstat to the ON function, still the same thing. once the ac kicks on, the indoor fan kicks off. is there a way to by pass that?
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.
Welcome! We keep going until you have all of the information you need.[b/]. Extensive training & coaching also available.

Tell me your fan is variable speed, those come on very gently and vary their speed with the load...and have more than 6 wires attached and no run capacitor... that cannot be hot wired.

If you have two or three fixed speed blower motor with only 4 or 5 wires attached including a run capacitor, it comes on suddenly and is quite noticeable.. then that can be hot wired to run all the time, but does take some skill and coaching.

Let me know, we can go from there.

Customer: replied 2 years ago.

Hello, from what the schematic indicates, the blower is a 3 speed. black for high, blue for medium and red for low speed. there is 5 wires coming from the tstat with 2 additional wires going out of the board as well the colors on the circuit board are marked as follows with the corresponding color wire:

Y terminal - yellow wire connected

W terminal - green wire connected

R terminal - black wire connected

G terminal - red wire connected

C terminal - blue wire connected

additionally there are 2 more wires coming into the board, a black and green (looks like they are going to the condenser).

the black wire is connected to the y terminal

the green wire is connected to the C terminal

Customer: replied 2 years ago.

My brother in Law is here now, he is a licensed HVAC technician, have a good day...

Expert:  Phil replied 2 years ago.
You are fortunate! Stay in touch if you need us.