AC indoor blower fan trying but not holding...


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Old 04-14-18, 04:03 PM
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AC indoor blower fan trying but not holding...

My AC blower has an intermittent thumping sound every two seconds or so, as it tries to kick on. The squirrel cage turns very slightly. When I push it along a little faster, it starts to engage for around 5 seconds or so, then shuts back off. The squirrel cage feels pretty free, no bearing issues or gunk. It makes me think there's a run capacitor that needs replacing, but if so, it must be internal to the motor... I do not see one anywhere. It could be that the motor is not getting enough juice, but I'm only so-so with a digital multimeter and am not sure what voltage, amperage, etc. it should have. Best I can tell, it's a GE 1/2 HP CN02 motor. Any thoughts on what to check next? Oh, there are no overflow switches, door switches, fuse resets that are in play. The motor is from 2001. Any thoughts on next troubleshooting steps?
 
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Old 04-14-18, 04:37 PM
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I'm not certain, but it appears that your motor may be an ECM (Electronically Commutated Motor). They are very energy efficient and are variable speed and don't use a capacitor. While there are many advantages to the ECM motors, the downside is that they are very expensive, typically ~$1000. The ECM motor in my York high efficiency furnace failed (fortunately, it was still under warranty). The technician who came out to diagnose the problem said that there is test equipment that can determine whether the motor is bad or not. There is an electronic control module that's bolted to the back of the motor. Often, if there is a problem with the motor, the problem is in the control module, which can be replaced by itself, rather than the complete motor assembly (control module plus motor).
 
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Old 04-14-18, 04:51 PM
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Welcome to the forums.

Yes... that is a GE GENTEQ ECM motor. Bob did a good job of explaining how they operate. They are not an easy DIY repair. You can look up Genteq ecm motors and there are videos on you tube that illustrate diagnosing and repair.

I was going to mention checking on your warranty status but that has long expired.
 
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Old 04-15-18, 10:17 AM
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Thanks all! I think you're spot on with the assessment. It's time to call the pros. I'll reply back with details for posterity.
 
 

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