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Discussion Starter · #1 ·
This is a 15 yr. old furnace, and after troubleshooting it gives me a code 42 which indicates ( no start on Inducer fan motor or not working at proper RPM).
Am I missing something?
I performed a diagnostic test with dip switch which turns all components on in the proper sequences of operation. Again the inducer fan doesn't turn on, the pressure switch, igniter and blower does. That would tell me that inducer fan motor is out.
Next I put my meter to the end of the small harness that connects on top of the inducer fan motor box, and I get 120 volts. It's a 2 speed inducer motor ( Low/High).
QUESTION: My guess it's the inducer motor, but could it be the main control board?
 

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your presure switch closes with the IDM dosnt even turn? is it stuck close. some cpu logic wants to see that switch open before start up.
 

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15yr furnace I would say bad motor. like one other said if you are getting 115 at the motor when it"s calling and does nothing motor is bad.
 
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