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M Oglesby
M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience:  Universally Certified HVACR Technician
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My daughters coleman evcon is flashing 3 times, the combustion

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My daughters coleman evcon is flashing 3 times, the combustion air switch is not closing. I trimmed back the tubing to get better connections, no help. I can pull off one of the tubes from the combustion air motor assembly, suck on it, pinch the tube flat and the furnace will cycle. There doesn't seem to have any suction from the combustion air motor assembly. Should there be suction that you can feel when it is working?? Can it be repaired or do you have to replace the entire combustion air fan motor assembly?? Do you need to remove all the sheet metal screws from the plate behind the gas valve to get room to remove the combustion air fan motor assembly?? Thanks. Jay

M Oglesby :

Remove the rubber hose from the combustion fan motor.

M Oglesby :

Stick a long thin nail or a paper clip in the connection at the combustion fan motor. Make sure the nail goes all the way through touching the fan blades.

M Oglesby :

Apply a little force if necessary to make sure this connection is not blocked.

M Oglesby :

Also go outside and make sure the flue vent pipes are not blocked with debris, birds nest, wasp nest, etc...

M Oglesby :

If this does not correct the problem, then you will need a new pressure switch. I believe you call it the air switch.

M Oglesby :

Please hit ACCEPT if you are satisfied with this answer. Bonuses and positive feedback are very much appreciated!


The flue is not blocked. Do you want the nail in the brass connector at the top or the black plastic coupler at the bottom??

M Oglesby : Whichever one the rubber hose is connected to on the combustion fan motor.

It looks like the paperclip trick worked. Thanks

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