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I have a furnace model 912SB48080S174A-A and it is not

Customer Question
I have a furnace...

I have a furnace model 912SB48080S174A-A and it is not heating the flashing code is 3 shorts and a long, can't find the manual so what is the problem?

Contractor's Assistant: Did you double-check the thermostat's settings? And what about the filters?

Yes, even changed the batteries, and the filers are changed every month, switch is in the "on" position, no breaker problem in the box, so I've done the preliminary stuff.

Contractor's Assistant: Do you plan on doing the work yourself?

Depends on what it is.

Contractor's Assistant: Anything else we should know to help you best?

Like what? The furnace is about five years old.

Submitted: 8 months ago.Category: HVAC
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Answered in 8 minutes by:
12/14/2017
HVAC Technician: airheatman, HVAC Technician replied 8 months ago
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 9,376
Experience: Furnace, A/C and heat pump specialist.
Verified

The 31 is an open pressure switch code.

This means the inducer is not pulling sufficient vacuum on the pressure switch or the switch is defective.

Troubleshooting may require a multi meter and a manometer to test the switch.

If you have or can obtain these I will be happy to guide you.

Otherwise you will need to get an onsite tech with the test equipment to determine why pressure switch is not closing.

If you would like to troubleshoot, please rate answer below and I will be happy to guide you in troubleshooting.

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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 9,376
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