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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8326
Experience:  Furnace, A/C and heat pump specialist.
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Tom, I have a tough question . I've replaced my capacitors, fan motor, and

Customer Question

Hi Tom, I have a tough question for you. I've replaced my capacitors, fan motor, and contactor, but the compressor fan runs intermittently. Most of the time, it starts along with the compressor (which is running fine, by the way) but it will drop out after 10-45 minutes. I have 24v across the contactor (thermostat side) and about 245 across the terminals. great voltage coming off the compressor cap, and when the fan is running, I get about 370 at the fan cap. then the fan stops and I have nothing at the fan cap.
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.
Hello. My name is ***** ***** I'll do my best to help. Let's get started and see what we can do.PLease give me a bit more info.
1. Do you have a dual cap for compressor and fan?
2.Model on outdoor unit
3.Explain the "I get about 370 at fan cap"
4. Are you saying 370 volts and where exactly are you checking?
5. You should never have more than 253 volts anywhere in the unit
Customer: replied 2 years ago.
1. Initially I had a dual cap, but now I have 2 capacitors.
2. The outdoor unit is a Rheem Classic Series High Efficiency
3 and 4. During operation, I'm measuring approximately 370v AC across the fan capacitor terminals.
5. Across the contactor terminals I read a pretty consistent 245 volts.I think the fan may have been overheating. I sprayed down the coils and (with a garden hose) to remove the dirt and grass that had accumulated on the side to see if that will help it operate longer.I also believe that I am running low on refrigerant. the cold pipe feels just a little chilly. not really cold.
Expert:  airheatman replied 2 years ago.
OK with a separate capacitor. we should not be getting a volt reading at capacitor. We want to check the two power wires from contactor to motor.If we are getting 245 to those wires and cap is good, motor should stay on.
Do you have an amp meter to see what fan is drawing just before it shuts off?
Customer: replied 2 years ago.
fan was drawing 1.3-1.4 amps, which is what it's rated for. looks like cleaning off the coils might have taken care of the issue. The unit is old, so I'll probably have to replace the compressor in a year or 2, but everything is working now.
Expert:  airheatman replied 2 years ago.
Excellent. motor may have been overheating due to high head pressure and temp if coil was dirty. Just let me know if it gives you any more issues.