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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8138
Experience:  Furnace, A/C and heat pump specialist.
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I have a mobile home with a Nordyne unit E2 EB012 HB heat pump.

Customer Question

I have a mobile home with a Nordyne unit E2 EB012 HB heat pump. The inside unit seems to work fine but the outside never kicks on in either heat or cool.
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.Do you have a meter for troubleshooting? If so provide me with model on outdoor unit and we will go from here.
Customer: replied 2 years ago.
Yes I do. Model Number is *****
Expert:  airheatman replied 2 years ago.
Excellent, let me pull a manual on the unit to look at wiring. Have you checked for 230 volts at the outdoor unit?
Customer: replied 2 years ago.
I have verified the voltage and it is present. If I manually press in the contactor, the fan and compressor start. I have 24V on the wires that go to the defrost board, but when I plug the wires in the 24V is gone. I replaced the defrost board with no change.
Expert:  airheatman replied 2 years ago.
Disconnect the low voltage wires from the contactor (I think they are blue and black) and see if we still lose the 24v at board
Customer: replied 2 years ago.
voltage stayed at input to defrost board and now the unit hums when power is on. The 24v measured 21.
Customer: replied 2 years ago.
What should the resistance on the contactor relay be?
Expert:  airheatman replied 2 years ago.
Not sure what would be making the 24v drop to 21 with contactors disconnected, but if voltage stayed , sounds like contactor coil may be bad. I would replace contactors as they are less than 10 bucks at appliance parts store.
Expert:  airheatman replied 2 years ago.
Contactor coil should have between 9 and 12 ohms of resistance
Customer: replied 2 years ago.
measures 16 ohms, the humming was not present last time(before replacing the defrost board),
Expert:  airheatman replied 2 years ago.
If over 12, replace the contactors
Customer: replied 2 years ago.
Bought a new coil and it also measures 16ohms. No change in unit function. 24 V is present at defrost board until the thermostat is switched to the "Cool" position. Then it goes away. Contactor is not pulling in. When the contactor is pressed in manually both the fan and compressor start.
Customer: replied 2 years ago.
Does my system have a low pressure switch and is there a way I can verify that is the problem without having to pay for a service call first?
Expert:  airheatman replied 2 years ago.
I do not see a low pressure switch on the wiring diagram.But eve if it had one, we should still get the 24v out of the defrost board just not to the contsctor.I though sure the contactors were the issue as that seems high ohms.
See video below:
https://www.youtube.com/watch?v=qRPCkq9ADng
I am now wondering if maybe you got a DOA board out of box.
Customer: replied 2 years ago.
Diagrams on inside unit show a limit switch. But there is no more info on it. I'm thinking this could be one of the pressure switches. I haven't physically verified that it's present yet. Should do that tonight.
Expert:  airheatman replied 2 years ago.
I am not showing a low pressure switch in the diagram.