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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a concord 80 plus gas furnace with no heat. Just vent

Customer Question

I have a concord 80 plus gas furnace with no heat. Just vent blower. Circuit board is flashing 4 times which the diagnostic label on the inside cover says it is a high pressure switch open. I'm trying to find location and how to test it
JA: Did you double-check the thermostat's settings? And what about the filters?
Customer: the thermostat is a manual slide unit and appears to be ok. the vent blow is responding to the on off and low temperature setting. Vent blower comes on when high temp is selected. Filter is ok
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: it was working when I turned it on a month ago to test it.
Submitted: 15 days ago.
Category: HVAC
Expert:  airheatman replied 15 days ago.

Can you give me complete model from inside furnace in burner compartment so I can provide guidance with this specific unit.Model will be on a label just above burners on right or left inside panel

http://i.imgur.com/U8b0GXT.jpg