Skip to main content ↑ ↓
Topic: Problem with Dometic roof mounted AC & Heat Pump (Read 1298 times) previous topic - next topic

Problem with Dometic roof mounted AC & Heat Pump

We having a problem with our Dometic model 630215.321 in our '99 U320.
The fan motor needs a nudge to get it going. Just replaced the AC starting capacitor and that didn't help. The fan turns freely, just needs a nudge to get up to speed. AC works, just no fan, except when I nudge the blades.

Everything that I read suggest replacing the motor. Price seems to be between $100-150.

Has anyone done this or is this the time to replace the whole unit?  Best price on new is $1175.

Dick & Sue
'99 U320, 36'
2015 F150 4x4 Supercrew
M & G with brakeaway system
Blue Ox Avail 10,000# tow bar
Grosse Ile, Mi.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #1 –
Did you replace the run Capacitor.
The selected media item is not currently available.Bill&Doris 97 U270 36'
University of Parris Island Class of 66
Semper Fi  Build# 5174 MC#17094

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #2 –
Don't know if it is true with your Dometic, but ours has a fitting on each end of the blower motor calling for oiling. The shroud has to be removed up top in order to access the motor, etc.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #3 –
I would have to nudge my fan to get it started also until it quit completely. I got my replacement off Ebay. Easy swap out and it has run fine for 3 years.
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #4 –
nitehawk..... the earlier blower motors had oil ports. The later ones like ours have sleeves. Some oil may help it to last longer. Once I nudge it, it runs fine. Just does't want to start.

Bill.... just replaced the start cap. None of the service notes that I found suggested the run cap.

Jerryetc.....The motor does look like an easy swap out. May wait until we get home. The other problem is the cover is showing signs of uv damage. Will need to add that to the cost of a new motor vs replacing the whole unit.
Dick & Sue
'99 U320, 36'
2015 F150 4x4 Supercrew
M & G with brakeaway system
Blue Ox Avail 10,000# tow bar
Grosse Ile, Mi.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #5 –
Remember when you change unit the board in the AC has to match the board in the t-stat on the wall, meaning a new Dometic 15k /heat pump (Penguin) will come with a 10 button board in it, your coach probable has a 4 or 5 button controller so 2 options if your coach has a 4 button control you can't get boards for that one so you will have to change t-stat on wall and replace other boards  in the other AC's to match , If you have a 5 button control in coach you can buy a new 5 button board for the new AC 
Art
1997 Prevost 40'
 The selected media item is not currently available.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #6 –
Dick,

You may have installed a bad capacitor.

I know this is a dumb question but are you sure that you changed out the start capacitor for the fan and not the one for the compressor?

With the symptoms you describe it points to a bad start capacitor.

By the way was your capacitor hid behind a little cover on the passengers side of the unit?  If so some of them were a duel capacitor that is about the size of a roasted hops soda pop can.  If you have one of those are you sure that you reconnected the wires back to the proper location as they won't work if hooked up wrong.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #7 –
The Dometic 4 button thermostats are repairable. There are no new ones available anymore so repair is the easiest and most economical way to make the system work properly again. Four and five button AC boards are available.

Jim
Jim Frerichs
2002 U320 42'

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #8 –
prevostart......Thanks for the heads up on the replacing the new board for the new unit. We replaced the 4 button stat and boards about 8 years ago. We'll put that into the replacement/repair cost.

If anyone is interested, we still have the old 4 button stat and both 4 button boards. They could be looking for a new home.

Mike..... It could be possible that the new start cap. could be bad, but not likely. The run cap is a 3 tab capacitor. Yes it's located under a cover on the pass side. With only 2 wires to hook and no markings on the cap., it would be easy to hook up wrong. There is a vent "hole" that I used as a guild.
Dick & Sue
'99 U320, 36'
2015 F150 4x4 Supercrew
M & G with brakeaway system
Blue Ox Avail 10,000# tow bar
Grosse Ile, Mi.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #10 –
Dick, google wiring diagram for the model number for your unit, it will show the lead from the run cap, split phase motors need a run cap, it would be worth a try and see if it corrects the problem before you replace the unit.
The selected media item is not currently available.Bill&Doris 97 U270 36'
University of Parris Island Class of 66
Semper Fi  Build# 5174 MC#17094

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #11 –
Hi Dick,

Yes, I would be interest in your thermostat and board.

Jim

308-440-5154
Jim Frerichs
2002 U320 42'

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #12 –
If the fan motor turns with (a little) resistance, look into oiling or pulling it apart and clean or replace the bearings or selves. 
If the motor has not generated the smell of electrical insulation (started to burn up,)  I'd guess the motor is good to go.

Unless your unit has a sealed electric motor and has not burned up, it can be fixed.
Find a article on small electric motor repair if you need courage... go for it.  pc

S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #13 –
Another winkle, motor runs about 1/2 to 1 hour and stops. Turn of stat for about 10 mins and nudging will restart the motor.

pc.... The fan blades turn freely, except when trying to start. That's where the nudging comes into play.
Dick & Sue
'99 U320, 36'
2015 F150 4x4 Supercrew
M & G with brakeaway system
Blue Ox Avail 10,000# tow bar
Grosse Ile, Mi.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #14 –
inspectapedia.com

Excellent source for the neophyte small electric repair person..  pc

After checking,
seems the problem may be the centrifugal switch is having issues.. ?
S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #15 –
We oiled ours with a spout oiler.  We ran oil down the shaft on both ends of the motor.  I assume you have removed the roof cover and looked at the motor to see what you could see.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #16 –
I got quite a few motors to run a bit longer with Lube 1 it has slick 50 Teflon in it it stay's for a long time and you can lube both ends of motor
Art
1997 Prevost 40'
 The selected media item is not currently available.

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #17 –
Quote from: Dick & Sue –
Another winkle, motor runs about 1/2 to 1 hour and stops. Turn of stat for about 10 mins and nudging will restart the motor.

pc.... The fan blades turn freely, except when trying to start. That's where the nudging comes into play.

Many electric motors have a built-in thermal overload switch, so if bearings are dragging and it's heating up the motor the motor will run for a while, stop and cool down, and cycle again. Lube the bearings may buy you some indefinite time, before replacement. Maybe hours or maybe months or longer.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Problem with Dometic roof mounted AC & Heat Pump

Reply #18 –
Duh phred 120 volt call a local appliance parts store, or Washer Specialtys in Wichita, KS Washer Specialties
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake