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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My furnace is flashing red 3 times. appears to turn on but

Customer Question

my coleman furnace is flashing red 3 times. appears to turn on but blowing cold air. does not appear to be igniting or using the gas....propane. tank at 75% all other gas appliances working in house.
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
it's 4 flashes not 3
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  airheatman replied 1 year ago.

Can you give me the complete model number on the furnace? It will be on a label on inside furnace panel just above burners.Remove panel to burner compartment and look inside. The model number will help me give accurate assistance for your specific unit.

Below is a link showing where to find label with model number:

Customer: replied 1 year ago.
Expert:  airheatman replied 1 year ago.

OK turn power off to furnace and back on to reset board. See if furnace tries to work or we get same code.Also let me know if you have a volt meter for troubleshooting.

Customer: replied 1 year ago.
same code.
Expert:  airheatman replied 1 year ago.

OK the 4 blinks indicates that we have an open limit switch,you may have several. Lets start with the ones that are resettable. Button in center will push in and click to reset.

Customer: replied 1 year ago.
reset 2. One on the blower and one on the gas port. Still same. .
Expert:  airheatman replied 1 year ago.

OK our next step is to trace the limit circuit.First unplug the plastic 12 pin connector on board and make sure all wires are seated in plug so they make contact when plugged onto board.If all are good, follow the limit circuit and check each limit in the circuit for continuity.or by bypassing each one, one at a time.

I have highlighted the circuit for you in diagram below to make it easy to find the limits.