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Topic: Dometic AC Motor  (Read 473 times) previous topic - next topic

Dometic AC Motor

     My back AC unit has worked well these last 3 years.  Down here in Florida it has been running quite a bit.  All of a sudden it wasn't blowing like it usually does.  When I got close to the vent, I could feel the cold air, but it wasn't blowing.  It was making a normal noise but no blowing.  So, I went up top while my wife turned it on.  The motor made a humming sound, and I could feel it vibrating but didn't turn. The compressor appeared to be working.
    I don't know enough about this to proceed. Should I replace the motor or call a technician or just replace the whole unit.  It's the original unit.  I believe the older ones are built better and last longer than the newer ones.



Rick & MJ Berry
1998 U320 40'
Ohio

Re: Dometic AC Motor

Reply #1 –
First step is I'd change out the capacitors, cheap and much easier than changing the motor (which may not be available).
Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
no longer 1999 36' U320 build #5522
2013 Rzr 570 & 2018 Ranger XP1000
2006 Lexus GX470
2011 Tahoe LT 4x4
Previous 1998 45' 2 slide Newell, 1993 39' Newell

Re: Dometic AC Motor

Reply #2 –
The condenser fan motors are available, as I have a new one in the shop I bought from Johnstone Supply last year. They are generic double shaft motors. I will look in the shop tomorrow and get numbers off it. Change the capacitor first to see if it fixes it.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Dometic AC Motor

Reply #3 –
Quote from: 18360 –
    I don't know enough about this to proceed. Should I replace the motor or call a technician or just replace the whole unit. 
Hello Rick,

When you were up top did you remove the plastic shroud?  If you did, you are 2/3 of the way to fixing it yourself.  This can be very satisfying. 

As Forest said, it is almost certainly the capacitors that have gone bad.  The way to confirm this is when you are up top and you have your wife turn the A/C on and the motor is buzzing, give the squirrel cage fan a little push and if it then begins to run on it's own, you have identified that that the problem is the capacitors. 

There are likely two can shaped capacitors with two to four wires connected to each.  Take a picture before you remove them then take them out and take them to any plumbing/air conditioning supply house and they can sell you new ones.  The volts and micro farads (u/f)  numbers on the old and new capacitors don't have to be exactly the same but should be in the same range.  And you might as well replace both at the same time.  The two capacitors will cost a fraction of what a service call would be. 

I have had to replace the capacitors on both of my air conditioners at different times.  The first one was easy and the second one was a piece of cake. 

Good luck,

Richard
Jan & Richard Witt
1999 U-320  36ft WTFE
Build Number: 5478 Motorcade: 16599
2011 Jeep Wrangler Unlimited w/Air Force One
Jan: NO5U, Richard:KA5RIW
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Re: Dometic AC Motor

Reply #4 –
Thanks.  We will do that.
Rick & MJ Berry
1998 U320 40'
Ohio

Re: Dometic AC Motor

Reply #5 –
This is the motor for the Dometic Penguin. The capacitor was for both the compressor and the fan motor.

1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Dometic AC Motor

Reply #6 –
We used a Zoom oiler to lub both ends of blower motor. Try to rotate the motor shaft to get oil into the bearing. Capacitors should also be replaced, often ahead of problems.

Re: Dometic AC Motor

Reply #7 –
And, many small containers of sewing machine oil have enough of a spout to get where you need to lube.

Of course, you can always dip the end of a clean screwdriver in the oil and use it to transfer the oil.  That is how I do it when lubing the furnace fan motor.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Dometic AC Motor

Reply #8 –
     The cage did start spinning and I'm getting cold air.  So do I loosen all of the little bolts on the inner shroud and is that where the capacitors are?
Rick & MJ Berry
1998 U320 40'
Ohio

Re: Dometic AC Motor

Reply #9 –
I turn off the breaker, pulled the side panel and took pictures and pulled the wires.  Now I'm going to try to find the capacitors locally.
Rick & MJ Berry
1998 U320 40'
Ohio

Re: Dometic AC Motor

Reply #10 –
Quote from: 18360 –
I turn off the breaker, pulled the side panel and took pictures and pulled the wires.  Now I'm going to try to find the capacitors locally.


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Joe & Dottie Allen
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