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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22110
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a PG8MAA036070 furnace that the blower won't shut off.

Customer Question

I have a PG8MAA036070 furnace that the blower won't shut off. It only shuts off when switch to off
Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.
Hello, there are only 2 choices....there is a short in the thermostat or thermostat wire....OR...the circuit board is bad. If you remove the green thermostat wire from the circuit board G terminal...and blower continues = bad board
Customer: replied 1 year ago.
Ok I replaced digital to Mercury stat and still doing same. I ohm stat wire and ohm ok. So you telling me that if I disconnect the fan green wire from board and still runs then bad board. Could it be a dirty sensor or bad limit switch
Customer: replied 1 year ago.
It will shut off if stat is switch to off position
Customer: replied 1 year ago.
Hello
Expert:  BillyHvac replied 1 year ago.
if it were a bad switch you would have no heating or cooling....if you have function but blower runs nonstop it is circuit board
Expert:  BillyHvac replied 1 year ago.
does fan run non stop in auto?
Customer: replied 1 year ago.
Yes it runs continuously on auto
Expert:  BillyHvac replied 1 year ago.
May I ask how wires are attached in furnace and in thermostat (color to terminal)
Customer: replied 1 year ago.
I disconnect low voltage from the board and stat ohm it out and ohm ok
Expert:  BillyHvac replied 1 year ago.
ohm will only tell us if open, not shorted
Customer: replied 1 year ago.
Board to stat
W-W
G-G
Y-Y and W condenser
R-R
Common R condenser
Expert:  BillyHvac replied 1 year ago.
ok I am confused on "and W condenser R-R Common R condense" is red wire to R in stat and at boardwhite wire to w in stat and boardyellow to y in stat and boardgreen to g in stat and board Then the 2 wires from ac:one on Y with the thermostat yellow and one on C?
Customer: replied 1 year ago.
Yes correct
Expert:  BillyHvac replied 1 year ago.
thank you. If board were bad....the blower would not shut off when switched to off from auto. when blower is running nonstop just remove that green wire from g....if it stops it is in the wiring..if it does not it is in the board

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