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My Coleman furnace would not start. The diagnostic board light was blinking 3 times. That meant the COMBUSTION AIR SWITCH FAILED TO OPEN. I ordered 2 switches from you folks. I installed it and the furnace still did not go on. I heard a loud buzzing coming from the STANDARD AIR BLEND 2 control box and 1spade was all rusty. Would that be my problem or do I have other problems?

Hi,

The blend air system is wired into the circuit, but not part of the cycle. Only way it would come into play is if something wrong with splice where it is wired in interrupted the circuit.


Combustion air switch failed to open/close can be any or a combo of these:

bad pressure switch
kinked, loose, clogged tubes connecting to pressure switch
air pipe leading to combustion air/booster motor clogged or separated
combustion motor wheel dirty or damaged
combustion motor not running or not reaching enough rpm to produce correct water column pressure to switch



Thanks,
Robert

Thanks to all of you for all the help. I finally got to the bottom of my problem. It was the COMBUSTION VENTOR ASSEMBLY MOTOR was locked up.

You're very welcome, happy to help.



Thanks,
Robert