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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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American Standard 80 unit. Error code 4 thermal protection

Customer Question

American Standard 80 unit. Error code 4 thermal protection device open. I took the safety switch out, tapped on it and put it back in. Still same error code. Any suggestions?
JA: How old is the appliance? Have you gotten error messages before?
Customer: the unit is roughly 25 - 30 years old. Never had the error code before. Initially, the exhaust fan was constantly on, no blower motor but did have the burners working. Turned the unit off, turned off the switch for the gas, turned the unit back on, but the blower motor still did not run. Had a repairman look at the unit, he tested some wires, got the blower motor working, and seemed all was fine.
JA: Do you plan on doing the work yourself?
Customer: Now, blower motor and exhaust fan are running constantly, but no burners
JA: Anything else we should know to help you best?
Customer: I can get you the model number
Submitted: 8 months ago.
Category: HVAC
Expert:  BillyHvac replied 8 months ago.

it could also be a flame roll out switch located at/around the burner.

To eliminate we need to remove the wires from the limit and hook direct together.

Can you take a pic of the top section of furnace with door removed and post here using the attach files link?