Original message
| richsp2
|  "How to Wire Dual Cap to New Fan Motor"
, posted Fri 11 Jun 16:23  
Please Help. I have a Rheem Central Air Conditioner. The fan motor internally shorted to ground and needs replacing. The problem is that the old motor (single phase) had only two leads while the new motor (single phase) has two extra leads for a 5 mF run capacitor. What do I do with the old dual capacitor?
I understand that I should wire the new two-terminal 5 mF capacitor to the new motor's two brown leads. Is there any rewiring required of the old dual capacitor.
The Dual Capacitor is wired differently than you would expect. The 'C' terminal is wired to the 'S' terminal of the compressor. The other terminals are labeled "A" and "B". The "A" terminal is wired directly to L3. The "B" wire is wired to T3 of the contactor (there is a NC contact between L3 and T3 of the contactor). The old motor was wired to T1 and T3 of the contactor. Finally, there is what appears to be a resistor across the "C" and "A" terminals of the Dual Capacitor.
I can't tell which side of the capacitor was for the fan (if any). Is rewiring of the Dual Cap. necessary? Someone that I don't necessarily trust told me to short out the "C" to "F" of the Dual Cap. First, my Dual Cap is labeled "C", "A", "B" and second I can't tell which side of the Dual Cap is for the fan. Maybe both sides of the dual Cap are for the compressor?
Please help.
RichSP2
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Replies:
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| xenos
Webmaster 
| "Re(1):How to Wire Dual Cap to New Fan Motor" , posted Fri 11 Jun 17:16
Just disconect the fan motor from it and leave it wired to the compressor( don;t change any wiring). Then just wire in the new fan motor with the new cap.
Xenos.
The best way to escape a problem is to solve it.
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| | richsp2
| "Re(2):How to Wire Dual Cap to New Fan Motor" , posted Mon 14 Jun 09:55
I guess you're saying that in my case both sides of the dual capacitor are for the compressor?
I looked up the model number (F55HXCWT-1579) and part number (51-20671-01) from the nameplate of the old motor. Emerson says it's a PSC motor. They have a new motor that replaces it that is 4 wires (two for the cap.) even though the old motor was only 2 wires. For clarification, how is it that the old PSC motor functioned properly when it didn't have it's own run capacitor and it doesn't appear that either side of the Dual Cap. were for the motor? Or were they?
Can this capacitance from the Dual Cap. cause any problems with the new motor?
Thanks,
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| | xenos
Webmaster
| "Re(3):How to Wire Dual Cap to New Fan Motor" , posted Mon 14 Jun 20:15
A duel capacitor has 3 terminals, only 1 side is for the compressor. How do you know the old motor was a PSC motor? if it was only 2 wires I would say it wasn't
Xenos.
The best way to escape a problem is to solve it.
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| | richsp2
| "Re(4):How to Wire Dual Cap to New Fan Motor" , posted Thu 17 Jun 14:03
I believe you were right. I looked more closely at the windings throught the vent holes and it looks like a shaded-pole motor. I must have misunderstood the Emerson Motor literature.
One last question:
The part's store gave me a Totally Enclosed Non-Ventilated (TENV) motor to replace the old one that was Open Vented. I asked if it would overheat and the clerk said it would be okay.
Is it okay to replace a Open-Vented motor with a TENV?
Thank you for your help,
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| | Xenos
Webmaster
| "Re(5):How to Wire Dual Cap to New Fan Motor" , posted Thu 17 Jun 22:08
I would expect it to be better. Lets not forget your motor will have air over it.
Xenos.
The best way to escape a problem is to solve it.
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