Carrier 9200 - inducer fan not running, error 31


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Old 10-20-19, 03:47 PM
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Carrier 9200 - inducer fan not running, error 31

Hello, looking for some help with my Carrier 9200 furnace. Noticed that it wasnít running the other evening, so I went and found the error code 31 (pressure switch or inducer).
No blockage in the exhaust or intake pipes. The small tubes connecting the pressure switch to the burner and condensate pump are also clear. What I noticed while I was checking these tubes is that the inducer fan is hitting its housing when it turns.

When I was initially looking at the furnace I turned on the power, blower came on for about 90 seconds and then just a humming sound - nothing else. After a few tries, the inducer fan began to start up, however it was so loud that I shut it down right away. Took the inducer assembly apart and found no issue inside. When the assembly is out of the furnace, the fan turns with no noise. When I put the assembly back in the furnace, the noise comes back. It seems like the fan never gets up to speed due to the fan hitting itís housing. After some research, Iím wondering if the motor grommets could be the culprit - the furnace is about 20 years old, and they do appear worn.

Questions:

1) Could the grommets be causing the inducer fan to behave this way? When I pull back on the motor it does seem to resolve the noise.
2) if the fan does not get up to speed - would this cause the furnace not to start up properly? Trying to figure out if this is my only problem.

See attached photo of the grommets on the inducer fan assembly.
 
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Old 10-20-19, 03:51 PM
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Old 10-21-19, 01:03 AM
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There could be too much play in the bearings and when positioned horizontally, the impeller hits the casing.

That furnace needs a inspection before money is spent on it, the secondary heat exchangers fail on them - plastic coating comes off and plugs it up, metal starts corroding.

The problem is specific to carriers/bryants. After 20 years i doubt it's still good and even if it is, you should probably still get a new furnace rather than replace the inducer - considering the high cost of carrier parts and the issues these units have.

With a bad inducer the only way to check is to pull the blower assembly and look under near the back for corrosion. It's not completely reliable way to check since the rusting and plugging up starts from the inside - once you see rust on the outside it's completely shot.

 
 

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