Quote:
Originally Posted by Smoky
Exactly what I had to do. I reset the switch before removing the furnace—that got the fan working, but not the heat. I pulled the unit and pulled out the sail switch. It was a little dirty; so I cleaned it. Tested everything before reinstalling and by golly it worked!
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Nice!
yea, its a complex system, but really there's only a few things that can go wrong:
-Fan blows - requires power and possibly resettting circuit board (button)
-sail switch - make sure air is blowing before lighting it up
-Temperature sensor/cutoff - can't be too hot or shuts down
-(dual) solenoid - redundant cutoff for gas flow - doesn't start unless above all check out as good and fan is active (as reported by sail switch)
-flame sensor - "Am i burning?"
-Ignitor - Go!
-Circuit board - ties it all together (this is an $80 part on Amazon, FYI)
If you do get it out, the sail switch and thermo cutoff can be tested with a multimeter - should be 0 Ohms when active.
If the fan is running, but you don't hear a spark, its likely the sail switch (more) or thermo (less likely) - the circuit doesn't try to light it if there's no air or too hot, shuts down and tries again in a few minute (x3)
If you hear a spark, but no fire, could be a bad/dirty/disconnected ignitor, bad/dirty flame sensor, or (unlkely) broken solenoid - no gas flow or no spark means it shuts down to avoid flooding the cabin with unburnt gas.
If everything else seems to be working, its the circuit board
I had the circuit board replaced twice
The ignitor cable was loose once
The sail switch was replaced once.
Then i spent 3 months on the phone to get a new furnace under warranty.
Good luck!