Dometic AC not cooling

[urnmor]

My Dometic AC is not cooling. The fan does run but no cool air comes out.

Some background

In January I had it at the dealer and they did their inspection and the AC was fine.
This is the first time I have used the AC since the inspection in January.
It has been hot with temps in the high eighties and low nineties.
I have used the heat pump earlier in the season with no issues.
It has rained hard at times but not recently

Having read other posts I am assuming it could be 1 of four things:
It has lost freon
Compressor has gone bad
Sensor has become lose
Board has gone bad.

So my question is where do I begin to fix the issue. Any suggestions are greatly appreciated

[wulfraat]

First thing I would do is physical inspection of the AC pan for oil. Go on roof, pull the AC cover/shroud, look for oil, if it's wet - you have a leak / have lost freon. Replace the AC unit. (Dometic penguin I/II are non-serviceable for leaks) ($1k+ installed)

The next thing to do is to put an ammeter on the common wire to the compressor. Should see surge on startup and then build up to and rest at ~11amps running. If you are only seeing 6-7-8 amps then you have lost freon pressure. (I have been here - no leaking fluid detectable but amp draw on compressor motor was low / meaning less resistance than normal). Replace AC unit. ($1k+ installed)

If you are getting 0 amps then and it is simply failing to even start rotation - move to start capacitor. To check the start capacitor, first discharge it, then using your multi meter to test the start capacitor for microfarads and make sure your reading aligns with it's rating (should be printed on the capacitor - look for MFD rating). If out of range after 4-5 tests, replace the start capacitor (~$20 bucks or so).

If compressor is starting but then fails to continue to run, check the run capacitor using the same method above. Change the run capacitor if needed. (~$20 bucks or so).

If capacitors are good, but zero amps to the compressor, then check all AC connections in the system. find the loose connection. $0 fix It is possible you have a bad board, but this is less likely. (need to check cost on Dometic Penguin board)

Bottom - line - you are looking to determine if power getting to the compressor, does it start at all / see any power, if it runs does it run at expected amps, or does it run and then stall........

That's about all I got my guess is bad capacitor or freon leak.

[urnmor]

[QUOTE=wulfraat;2516656]
The next thing to do is to put an ammeter on the common wire to the compressor. Should see surge on startup and then build up to and rest at ~11amps running. If you are only seeing 6-7-8 amps then you have lost freon pressure.

If you are getting 0 amps then and it is simply failing to even start rotation - move to start capacitor. To check the start capacitor, first discharge it, then using your multi meter to test the start capacitor for microfarads and make sure your reading aligns with it's rating (should be printed on the capacitor - look for MFD rating). If out of range after 4-5 tests, replace the start capacitor (~$20 bucks or so).

If compressor is starting but then fails to continue to run, check the run capacitor using the same method above. Change the run capacitor if needed. (~$20 bucks or so).

If capacitors are good, but zero amps to the compressor, then check all AC connections in the system. find the loose connection. $0 fix It is possible you have a bad board, but this is less likely. (need to check cost on Dometic Penguin board)

Bottom - line - you are looking to determine if power getting to the compressor, does it start at all / see any power, if it runs does it run at expected amps, or does it run and then stall........



Thank you for your reply
Am I correct in assuming the compressor and the capacitors are on the unit on the roof.

Also you think the heat would have an impact

[wulfraat]

Originally Posted by urnmor;

Thank you for your reply

Am I correct in assuming the compressor and the capacitors are on the unit on the roof.



Also you think the heat would have an impact

Yes, all of these items are on the roof unit, located under the white plastic AC shroud / cover.

Heat does not affect the unit’s ability to start and cool the interior air of the airstream. These units will run and cool in 120+ degree outside ambient air temperature.

Capacitors store 120v energy. Handling one the wrong way can have very serious consequences. If you are unsure about maneuvering on the roof of your airstream and/or working with live 120v systems you should seek the assistance of a certified tech.

Disconnect all shore power before removing any AC components such as capacitors. Discharge capacitors before handling them. Again, if you are unsure of how to perform these tasks seek the assistance of a certified tech.

Working with live 120v systems to measure things like amperage draw is serious business.

End of disclaimer……