Air conditioner acting funny

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New member
May 18, 2019
Hello folks,

One of my Dometic penguin II ACs is acting funny. As background, I installed 2 new capacitors (Start and dual) but I still experience the following.

1. When the AC is running fine on high-fan, and then I switch to low-fan.. it just stops running.. if I try to go back to high-fan.. it does not work and stays like that for a bit.

2. I have to shut it down and not use it for a good bit before trying again.. sometimes it starts back up just fine on high-fan, other times it won?t work (fan does not start or run) and I typically wait a day or so before trying again.

The fan motor seems to work on high when it decides to run and the compressor seems to always work fine when the high fan is running. As mentioned above, I replaced the 2 capacitors and checked all the wires and such. I even switched out the comfort control thermostat.. but still no change.

I also bought one of those booster Start capacitors. It did not make a difference when I installed it.

Any comments, recommendations or guidance would be greatly appreciated.

Thank you in advance

Welcome to the RV Forum Streff

Sorry I'm not going to be able to offer much help....But hang in there someone will be along that may be able to help.
Here's my best "guess", Streff:

First off, I doubt that there is anything wrong with your compressor.

Possible scenario: When you turn the fan to "Low" it (the fan) stops running ...... per your description.  When that happens, the head pressure climbs very rapidly and the compressor is overloaded.  There is an overload protection device that senses (too high) temperature and shuts the compressor down ????.. so save its life, actually.  Nowadays that device (a thermal/bi-metal type switch ?.. used to be called a "Klixon") is buried in the compressor motor windings and once it trips it can take a long time for the compressor motor windings to cool down enough to let the device reset ?.. lots of thermal mass there.  On residential units, I used to run a garden hose over a compressor to speed the "cool down" process up so I could take measurements and see what was going on quicker ?? since I was on the customer's clock, so to speak?.. and always running behind on service calls it seemed.

Your description sounds to me like you have a either: (a) a fan/blower motor problem, or (b) perhaps a problem with the relay that switches the fan from Hi to Low.

Could be other things, of course.  Hopefully others with "hands on" experience with the Penguin will chime in; especially if they have experienced the failure mode you describe.

Good luck with the fix, and safe travels.  Pls let us know what the problem resolution was ??.. adds valuable info to the knowledge base for all us other forum members. 
Getting past my bed time.  :)

EDIT: "so save its life, actually"  s/b " to save its live, actually"  My bad.
My back room air conditioner was acting similar.  Got on the roof, pulled the shroud off of it and sprayed WD40 on the bearings of the blower motor and it solved the problem.

Had to run it at least once a week or it would bind up again. 

Thank you very much for the replies,

I will check the relay and also lubricate the blower motor as recommended and go from there. I recall lubricating some of the moving parts of the motor when this issue started at the tail end of last season. But probably not as detailed as I should have. I will do a more comprehensive job this time and see what happens.

Thanks again to those who responded.

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