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Old 06-14-2009, 03:01 PM   #76
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Fan on Outside Unit reverses direction when compressor kicks on


It would be the internal motor wiring(the windings).

It just worn out, or a surge. etc.

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Old 06-14-2009, 07:38 PM   #77
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Fan on Outside Unit reverses direction when compressor kicks on


I would suggest checking that connector on the common terminal of the capacitor. I'll bet it is cracked and causing voltage issues especially when the compressor is short cycled. I've probably replaced 75 of these cracked sta-con connectors mostly on Lennox units. This is also why it fell off twice.
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Old 06-14-2009, 11:31 PM   #78
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Fan on Outside Unit reverses direction when compressor kicks on


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Originally Posted by beenthere View Post
Because the start winding is not engaged/energized while its running.

The short acts as a running shunt.

When the compressor tries to start. The voltage drops enough for the motor to slow down and bring the start winding back into the circuit. Since its shunted, it spins the opposite direction.
I am still not understanding this. You say the start winding is not engaged while running, so it is not a PSC motor?

Can you explain what you mean by "the short acts as a running shunt"?

If the shorted/shunted start winding starts it in one direction initially, why would it later cause the motor to run in the opposite direction?

Not trying to be pig-headed here but I would really like to understand why this is happening.
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Old 06-15-2009, 07:23 AM   #79
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Fan on Outside Unit reverses direction when compressor kicks on


A start winding is not engauged while running.
But, it is part of the circuit to run.

It supplies the back feeed voltage to the run capacitor.

The short/shunt may only occur when the motor is warm from running. Or may only occur after teh motor reaches X RPM.

The short/shunt in the start winding prevents the motor from reaching full speed. When the compressor starts. It takes enough voltage away, that the motor slows down enough to bring the start winding back in.
But because of the short/shunt. The start winding now wants to start in the opposite rotation. Because its magnetic poles are reversed.
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Old 06-21-2009, 01:52 AM   #80
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Fan on Outside Unit reverses direction when compressor kicks on


Quote:
Originally Posted by beenthere View Post
It would be the internal motor wiring(the windings).

It just worn out, or a surge. etc.
Thanks! That's what I thought too. I am going to unceremoniously pitch the old fan.

Quote:
Originally Posted by SKIP4661 View Post
I would suggest checking that connector on the common terminal of the capacitor. I'll bet it is cracked and causing voltage issues especially when the compressor is short cycled. I've probably replaced 75 of these cracked sta-con connectors mostly on Lennox units. This is also why it fell off twice.
The connector was the first thing the tech checked. It's ok. The capacitor was replaced on the second trip, and it's also ok now. We have had 80F weather all week and into the 90F today and yesterday. The AC is working great, so I am glad the problem is solved.

Thank you everyone for your help. I truly appreciate this forum. It's been very helpful and I learn a lot from you guys. Feel free to continue the discussion. I will check back every now and then.

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