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natev 08-07-2012 11:20 PM

Air handler blower motor
My air handler blower motor started "stuttering" last week. It's keeping the house cool but it will start up fine blowing air & then randomly stop for a second and start up again and stop for a second - sometimes a few times in a row & sometimes it stops for a longer period but never more than a second or two before it gets going again. .
There's no pattern to it - it's completely random & there are no "bad sounds" or smells...

Is this most likely the motor or could it be the fan relay? How do I test that?

I opened the air handler & it's horizontally mounted (mount is on the left) & it almost looks like I have to remove the heat pump element & electrical connections to get the squirrel cage out if I need to replace the motor - is there an easy way to get it out or does it just look more complicated than it is?

I'd like to figure this out before it stops completely & we're stuck with no AC in 100+ degree weather.

Any help would be greatly appreciated. I believe it may be Lennox or Carrier (outside unit is a Lennox but the only tag I was able to find near the motor was the fan wheel which is a Carrier wheel)

kok328 08-08-2012 07:56 AM

If you have the capability, check the motor's capacitor. If not, it is a inexpensive first guess to fixing the problem.

natev 08-08-2012 08:26 PM

Could the behavior of the motor I described (stopping & starting randomly) be a symptom of the capacitor going bad?
The capacitor is not mushrooming or anything I can see visually, unfortunately I don't have a meter that can test ferads.

kok328 08-09-2012 08:18 AM

yes, this is sometimes a symptom. Perhaps, you could have it tested or just replace it for around $20 or less.

natev 08-09-2012 11:26 AM

So I went to Grainger this morning & picked up a replacement capacitor for $6. Took me 7 mins to replace it & it's been through 2 cycles now without messing up! Hopefully that was what it needed - thanks for the replies!

kok328 08-09-2012 01:18 PM

Successfully troubleshooting HVAC without seeing, hearing or touching isn't easy.
An educated guess at best.

Congratulations !!

natev 08-09-2012 01:30 PM

One more question - what's the difference between a cap that says 50/60 Hz & one that says 60/50 Hz?
The guy at Grainger said it didn't matter since the voltage (370 VAC) & microferads (7.5) were the same...
Just wondering if that would affect anything...

Also - I better check with you to see if on a single run capacitor (the one with just 2 terminals) does it matter which brown wire goes to which terminal? Ie...does the one with the white stripe need to be on a specific terminal & the one without the white stripe on the other - only 2 terminals & only 2 wires...wondering if it matters which is which)


kok328 08-09-2012 04:40 PM

No difference between 50/60 Hz & 60/50 Hz, it's just the order that the manufacturer decided to print it.
In the USA, we are 60Hz.
Wire and terminal connections do not matter on this particular cap.

natev 08-09-2012 04:43 PM

Thanks again! Just wanted to make sure I wasn't going to blow anything up :)

natev 08-10-2012 04:20 PM

Ok - worked great yesterday & now it's doing the same thing this afternoon...could I possibly have gotten a bad capacitor then?

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