Rear a/c issues

[LaMonte Monnell]

I have a rear dometic a/c unit. The output is great and working right.
The issue I have encountered recently is its not shutting down completely.
After it cycles it still hums like its not turning all the way off like something is sticking.
Would this be a capacitor issue or something else. Most of the time it is ok, but does this non shutdown sporadically. I turn the a/c breaker off and wait a bit , turn it back on and its fine.

[Bill Lampkin]

Could be your tstat fan setting is set to run all the time. Tstat Fan setting set to auto will only run when A/C is on. See if the fan setting is set to Hi or low. 

[LaMonte Monnell]

thermostat is set to auto and fan setting is on high......

[Bill Lampkin]

Set the fan setting to auto.

[LaMonte Monnell]

Thermostat is set to auto and fan has a high or low setting... i have it on high.

[Bill Lampkin]

My suggestion applies to the newer Dometic 10 button thermostat. Yours may be different (5 button). We had to replace both tstats a few years ago when we put in new A/C units.

[Michael DeFalco]

you state its not shutting off all the way ?  is it still moving air ? or is it just making a noise ?

[LaMonte Monnell]

It just makes a humming noise like its not completely shutting off.
It is an intermittent issue that just happens occasionally. I have to turn the rear a/c breaker off to get it to stop.
Then usually its ok when I turn the breaker back on.

[Eric Maclean]

Lamounte
Not sure whether the hum you describe is the fan motor trying to start or the compressor running either way it would likely be a fault in either the thermostat or the control box . My guess would be a sticking relay in the control box

Eric

[LaMonte Monnell]

thanks Eric.