Dometic Duo-therm 630035.321 heat pump will not Turn On

Just a thought, there is a minimum ambient temperature required for the heat pump. Normally its 30 or 40 degrees. But temps have been colder than normal in many parts of the country. Is it possibly a low temp cut out?

I think the EMS is your problem. From the description I think the thermostat is commanding the unit to come on (relay clicks) but the EMS has killed the power.

The unit should have two motors, the blower and the compressor. Each has it's own start capacitor but power from a common source. Both caps blowing can happen but it's a bit of a long shot.

The wall thermostat and the associated relays you hear run off 12 VDC which is why they still work. Can you bypass the EMS to verify?

#Marc: I have the same problem, found mine about 2 weeks ago when I was exercising the Generator have not got it checked out yet. It is the back one like yours. Roy

Lug_Nut wrote:
Sounds like a possible capacitor failure. Typical symptoms have it trying to start and immediately shutting down. Good news, it is a cheap fast fix, if in fact, that is the issue.

A Failed capacitor on a Dometic will NOT kill power to Both the Fan and the compressor. One or the other will come on. The clicking sound he hears is probably the 12 volt relays on the AC control board responding to the actions of the wall tstat. Doug

#Marc wrote:
I am on 30amp service and the DW try to use the microwave while the AC was running but as per the energy management system works the AC turn Off and after DW was done with the microwave the AC start running again. This is the only thing that I remember happened in the last 2-3 days.

Turn the Genset ON and run the HP system on Genset to test the rear operation. The odds are your EMS system is doing its job. 30 amp service and trying to run 2 HP's is not enough service. EACH HP pulls about 14 to 15 amps. Also, Turn OFF the front HP. Turn the 12 volt disconnect OFF for 5 seconds and reconnect power. That will rest the EMS system. Try the rear HP ONLY. Your EMS system should indicate if the Power to the Rear HP is OFF. HR/Monaco products use Intellitec EMS systems. Does your EMS remote panel show the green lite for the rear HP? Doug

#Marc wrote:
Lug Nut, where is the capacitor located?

It is located in the roof unit on the AC power input circuit. Best to have an electrician replace it. Capacitor failures are one of the most common issues when AC's don't run.

Lug Nut, where is the capacitor located?

I am on 30amp service and the DW try to use the microwave while the AC was running but as per the energy management system works the AC turn Off and after DW was done with the microwave the AC start running again. This is the only thing that I remember happened in the last 2-3 days.

Sounds like a possible capacitor failure. Typical symptoms have it trying to start and immediately shutting down. Good news, it is a cheap fast fix, if in fact, that is the issue.

Did it work previously?

Anything particular incident since then?