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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Rheem 2 ton RPKB heat pump. Condenser fan motor is pulling

Customer Question

Rheem 2 ton RPKB heat pump. Condenser fan motor is pulling high amps and tripping out every 5 minutes or so on internal over loads. This apparently caused the compressor to lockup due to getting condensate in it. Have replaced the compressor, defrost board, capacitor, contacter and fan motor, but its still doing it. All connections have been checked. Coil is clean, and I checked the fan outside the condensder and its still pulling high amps. Checked capacitors, they are fine. Fan actually starts and runs well, it just gets hot and trips out.
Submitted: 5 years ago.
Category: HVAC
Expert:  Douglas replied 5 years ago.
Hi, I'm Douglas and I am here to help you resolve problems with your heating and cooling equipment.

Can you tell me what replacement fan motor you put in?

Customer: replied 5 years ago.
The orignial motor was an Emerson model K55HXKYG-9835. 1/6 hp 208-230 1ph 1075/900 rpm rated at 0.73 amps. The replacement motor is says ProTech, but other wise its dead identical right down to the tag. Both motors are doing exactly the same thing, runs about 5 min then trips out.
Expert:  Douglas replied 5 years ago.
ok so it's an OEM motor... let me pull a schematic...
Expert:  Douglas replied 5 years ago.
you said you replaced the capacitor then mentioned capacitors.

It should have a dual capacitor on it (3 sets of terminals). The fan should have the brown wire going to the fan terminal on the dual capacitor and the orange wire should go to the common (with another orange wire on it going to the contactor). Can you verify this is all correct?

The capacitor should have markings that say FAN, HERM and COM at each terminal.
Customer: replied 5 years ago.
When we replaced the compressor we replaced the dual capacitor with two singles. It is wired correctly, with a 5 uf capacitor on the fan motor
Expert:  Douglas replied 5 years ago.
ok, so wired this way, you have the orange or red from the contactor going to one terminal and continuing on to the motor, then the brown to the other terminal and then the black leading to the defrost control fan terminal....
Customer: replied 5 years ago.
Yep, orange wire off the contactor parallelling to the compressor and fan capacitor. Orange wire from same terminal going to motor. Brown wire on other terminal of capacitor going to motor.
Expert:  Douglas replied 5 years ago.
Ok... is the fan blade the original?
Customer: replied 5 years ago.
Yep, installed as per original, and the same as the unit sittingnext to it. Frustrating isn't it.
Expert:  Douglas replied 5 years ago.
are you close to the machine? Or is it at another location?
Customer: replied 5 years ago.
I'm close
Expert:  Douglas replied 5 years ago.
do you recall, does the compressor have a moled plug? (if so we can unplug the compressor so it doesnt run). Otherwise disconnect the compressor and engage the contactor. Measure the voltage at the two fan capacitor terminals while the fan is running. your meter will need to be set high enough to read around 370 volts ac
Customer: replied 5 years ago.
This will take a few minutes, your getting outside my comfort range. Why disconnect the compressor?
Expert:  Douglas replied 5 years ago.
we dont want to cycle it, I also want to see how the fan does when it's not sharing power with the compressor.
Customer: replied 5 years ago.
For what its worth its working now. I decided while I was disconnecting everything to put another new capacitor in for the fan. Its running right where it should be now, even thought the one I took out is still testing perfectly good.
Expert:  Douglas replied 5 years ago.
How did you test the capacitor? With a meter that reads mfd or using the ohm ?

(It all pointed to a capacitor)
Customer: replied 5 years ago.
tested by mfd and ohms. maybe some sort of breakdown under load
Expert:  Douglas replied 5 years ago.
If it checked out with the mfd, I am with you on the load thing

Glad you got it going

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