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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8438
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Unfortunately, I donot have a model number to this unit but,

Customer Question

Unfortunately, I donot have a model number to this unit but, it's an old comfort maker.
My problem is, only the blower comes on and the error code blinks indicating that there's a reverse polarity issue.
I googled RP but, I'm still not getting it. Please help!
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Is anyone there?
Expert:  Phil replied 1 year ago.

Hello, I am reviewing your question now.

Expert:  Phil replied 1 year ago.

If the furnace has been operating for sometime without this error code, it is likely a bad printed circuit board sending a bogus error code.

You can however do a rudimentary polarity check using a volt meter, check for voltage between the white wire and ground, if you get more than 3 or 4 volts, there a problem in your neutral circuit, inside the furnace or the house.

Expert:  Phil replied 1 year ago.

We can go from here without any time limits, this step one of what could turn out to be many.

Customer: replied 1 year ago.
with that said, would it possibly be sending off a bogus code with only the blower coming on? Nothing comes on but the blower in other words
Expert:  Phil replied 1 year ago.

There are two blowers, the inducer, and the main blower... if the main blower comes on without the burners on, that points to a bad printed circuit card in most but not all cases..

Tell me how many seconds it takes for the main blower to come on after a call for heat.

We can go from there, and be sure to specify which blower.

Customer: replied 1 year ago.
That's just never calls for heat.....I engage the door switch and the main blower comes on...hence the red light on the board gives a steady flash with the error code advising it's a reverse in polarity.
Expert:  Phil replied 1 year ago.

Hello again, what were the results of the polarity test I asked you to do?

Next disconnect the red thermostat wire and tell me if the blower still comes on when you engage the door switch or not... if the blower still comes on the printed circuit board is most likely bad, (95% chance of that, but not 100%)

Expert:  Phil replied 1 year ago.

Thanks for letting me work with you. When we are finished,if my answer has been polite, professional, and thorough,please locate the 'rate your expert button' and click one of the ratings .If you still need help let me know!.

Rating will not increase your charges, nor close the question, but is how I earn my living.