2017 21’ A/C troubleshooting

[Red Dog]

Starting to see a situation on our air conditioning unit and wonder if there is anyone out there familiar with this.

Thermostat set to Low:
Setting on Heat strip or AC
Hums only/ fan does not come on

Thermostat set to High:
Setting on Heat strip or AC
Fan comes on and all is fine

Thermostat set to Auto:
Setting on Heat strip or AC
Intermittent; sometimes
Hums only/fan does not come on and sometimes, blower turns on high and all is fine


Regards,

Fred M.

[Steven M]

I have to say that I am at a loss except for one thing. Isn't the A/C supposed to be started in Auto mode only then you select A/C or heat?

[Red Dog]

Originally Posted by Steven M

I have to say that I am at a loss except for one thing. Isn't the A/C supposed to be started in Auto mode only then you select A/C or heat?

I usually select the low fan setting to keep the air circulation going. Otherwise, the air gets stuffy inside the trailer.

[tdf-texas]

It sounds like the run capacitor for your A/C fan has failed. That's typical when the motor hums but won't start.

You need to make sure the the fan motor run capacitor is a 20 + 10 MFD 370v - that's the size the manual says it is but I would verify anyway. It is located next to the control board - remove the top cover and it should be on the side of the enclosure.

Dometic sells the capacitor for about $60 but the same capacitor is available from Amazon, etc. for about $14.

[Red Dog]

Originally Posted by tdf-texas

It sounds like the run capacitor for your A/C fan has failed. That's typical when the motor hums but won't start.

Dometic sells the capacitor for about $60 but the same capacitor is available from Amazon, etc. for about $14.

Thanks Tom! As soon as the rain lets up, I’ll climb up there.

Fred M.