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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 7743
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: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year 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 1 year ago.
Yes I do. Model Number is *****
Expert:  airheatman replied 1 year 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 1 year 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 1 year 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 1 year ago.
voltage stayed at input to defrost board and now the unit hums when power is on. The 24v measured 21.
Customer: replied 1 year ago.
What should the resistance on the contactor relay be?
Expert:  airheatman replied 1 year 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 1 year ago.
Contactor coil should have between 9 and 12 ohms of resistance
Customer: replied 1 year ago.
measures 16 ohms, the humming was not present last time(before replacing the defrost board),
Expert:  airheatman replied 1 year ago.
If over 12, replace the contactors
Customer: replied 1 year 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 1 year 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 1 year 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 1 year 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 1 year ago.
I am not showing a low pressure switch in the diagram.