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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Furnace will not turn on, The filter is clean and in place,

Customer Question

Furnace will not turn on
JA: Did you check the furnace's filters?
Customer: The filter is clean and in place
JA: Do you plan on doing the work yourself?
Customer: I would like to try to
JA: Anything else we should know to help you best?
Customer: Green LED light is on solid and red light is on solid
Submitted: 9 months ago.
Category: HVAC
Expert:  Phil replied 9 months ago.

Hello, that indicates a problem with one of the controls inside the furnace, we can however attempt a reset, that is a bit of a long shot however.

First make sure the air filter is new or cleaned, then turn power off to the furnace for 5 minutes, then turn the power back on.... tell me what if anything happens.

Also I need the full model number of the furnace, it is on a sticker inside the same compartment as the gas valve, and I need the approximate age of the furnace.

Customer: replied 9 months ago.
The error code is pressure switch open fault
Customer: replied 9 months ago.
Model- KG7SC 120D-45D
6 years old?
Expert:  Phil replied 9 months ago.

Thanks, ***** ***** switch is a round hocky puck looking device with 1/4" rubber tubes attached. It can have the following problems:

1. Water (condensate) can collect in the tube. ( blow it out)

2. The tiny orifice inside the nipples that the tube connects to, can be clogged, (clean them out with a paper clip wire)

3. The hose can have dried out and have splits in the ends. (trim the ends)

4. The switch can be bad.

Do 1-3 first, if that fails we can do more complex tests on the switch pressure operation.

Expert:  Phil replied 9 months ago.

Next test:

restart the furnace, if the small inducer blower fails to start, then the error code is bogus (happens about 30% of the time)... if the inducer fan starts, wait 2 seconds, then fit a jumper wire across the two terminals on the pressure switch and hold it in place for 70 seconds... if the furnace starts, we know the pressure switch is bad (90% chance of that)

10% chance the furnace vent pipe is clogged with a wasps nest, or the blower wheel on the inducer fan has fallen apart.