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View Full Version : Can you shorten the shaft of condenser fan motor


parnell
Jun 18, 2010, 03:56 PM
Ordered a new condenser fan motor. The shaft on the new motor is 2-3" too long. Can that be shortened? Also, the original motor was 1.50 A with internal capacitor of 5.00 Mfd-370 and has 3 wires. New motor is 2.0 A with internal capacitor of 7.5 Mfd-370 and has 4 wires. Do I send the new motor back or is this workable?

hvac1000
Jun 18, 2010, 04:03 PM
The new motor probably used 2 of the wires to connect to the capacitor and the other two wires go to the load side of the contactor. Unless the shaft length causes a problem with putting the top back on the outside unit leave it alone but if necessary it can be cut shorter.

I have NO idea exactly what kind of motors you have since you did not post part numbers/brands/.other info so take what I say with a grain of salt since I do not know for sure what you are exactly dealing with.

parnell
Jun 18, 2010, 07:41 PM
The A/C unit is Ruud UAMB-036JAZ. The current motor is GE in a model they don't make anymore (5KCP39GGS325S). 1/3 hp, 1075 RPM, 208-230 volts, 1.50 A, 60 Hz, Ph1, thermally protected, class B insulation, Cont. Air Over, Rot Cap 5.00 Mfd/370 V, 3 wires. Shaft is about 3" lg. The place I ordered from looked it up (with model & serial #'s from Ruud) and sent an A.O.Smith mdl # F48T12A01. 1/3-1/6 hp, Rot. Rev, Ser 20609FM, Type UF, 2.0 Amps, SF 1.0, Capacitor Rating = 7.5 Mfd/370 V, 4 wires, shaft is 6.5" lg. Same RPM, volts, Hz, Ph, insulation and therm. Prot. The original external capacitor is 50/5 Mfd 370 volt, dual round run cap. The new ext. cap. Is 55/5 Mfd 440 volt dual round run cap. I think that's all the info. I appreciate any help.

parnell
Jun 18, 2010, 08:20 PM
Forgot one thing.. motor has special screw hole mounting... screws onto sort of a bracket on the frame.

hvac1000
Jun 18, 2010, 11:49 PM
Xx

hvac1000
Jun 18, 2010, 11:53 PM
Forgot one thing..motor has special screw hole mounting...screws onto sort of a bracket on the frame.



You will have to use this for the new motor.

Capacitor to be used with new motor 7.5 Mfd/370

Special screw hole mounting? Are you telling me the new motor will not work because of this? It says the new motor you bought has 8 mounting holes in the outer case/shell of the motor.


K55HXTDD-8385
F48T12A01
5458, 2CDT8
51-20668-11, 51-23055-11
51-20354-11, 51-23053-11
Fasco D837
ORM5458
4 in 1 Multifit motor
Replaces 1/6-1/5-1/4-1/3 HP
1/3 HP 1075 RPM
2.0 amps, 208-230Volts
1 Speed
Rotation = Reversible
Shaft: 1/2" x 6 5/8"
Motor Diameter 5 5/8"
Sleeve Bearings
70 C Ambient Temp
8 Mounting Holes in Shell
Includes 7.5 MFD Capacitor

parnell
Jun 19, 2010, 07:48 AM
Just giving all the information when comment about screw holes was added. My concerns were the differences in the amps, internal cap. And wires on the new motor and the new external cap.'s Mfd & voltage was different. Didn't know if that affected anything else or was compatible with the system. When you said "Capacitor to be used with new motor 7.5 Mfd/370 " - are you talking about the external cap. Just found this one --Capacitor Dual Rated Rd. Run 55.0/7.5/370. That should be compatible? Thank you.

hvac1000
Jun 19, 2010, 10:47 AM
Just giving all the information when comment about screw holes was added. My concerns were the differences in the amps, internal cap. and wires on the new motor and the new external cap.'s Mfd & voltage was different. Didn't know if that affected anything else or was compatible with the system. When you said "Capacitor to be used with new motor 7.5 Mfd/370 " - are you talking about the external cap.? Just found this one --Capacitor Dual Rated Rd. Run 55.0/7.5/370. That should be compatible? Thank you.

It looks compatible to me since you posted the other capacitor was a 55.0 for the compressor usage. You just need to make sure that the new blower motor capacitor is of the value required by the motor manufacturer. That value is 7.5 according to the web site I looked at for your motor you posted you bought. Also note that the new motor must be wired EXACTLY as it says for the new motor.