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Topic: Replace Dometic roof AC with what? (Read 891 times) previous topic - next topic

Replace Dometic roof AC with what?

As I posted elsewhere, our rear AC above the bedroom is the original Dometic AC with a heat strip. Last week it started hammering like an engine throwing a rod. Really noisy. Sounded more like we were camped under a busy railroad trestle, and all the railcars had bad wheels.
So, does anyone have any recommendation as to a replacement AC that is quieter and will still fit the existing hole in the roof??
Our front AC was replaced before we bought the coach. It is a Coleman Mach. The inside cover is smaller than the original AC cover. I can see impressions in the vinyl and this cover is also shorter than the old one. Someone covered this problem with a white plastic outlet cover--one with out holes other than for mounting.
When checking I cannot find any data as far as required opening size for the new ACs.
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: Replace Dometic roof AC with what?

Reply #1 –
I replaced our Dometic with an Atwood Air Command .... Based on suggestion by a few others on this forum. The roof opening is a standard 14" square hole.
Inside shrouds are slightly different, the Atwood has slightly rounded corners rather than square. There are slightly visible impressions from the old shroud at each corner but only about an inch.
We have upholstery instead of vynyl so it's not that noticeable.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Replace Dometic roof AC with what?

Reply #2 –
Also..... The Atwood is quieter inside the coach but the interior fan does not cycle off as the Dometic does. It has a 3 speed fan and only runs as fast as needed when on "Auto". Or you can select a manual speed setting.
We still have the Dometic Penquin II in the rear bedroom as it still works well.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Replace Dometic roof AC with what?

Reply #3 –
Thank you. Will investigate tonight. Pamela & Mike provided another possible scenario I need to check out also.
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: Replace Dometic roof AC with what?

Reply #4 –
Check condenser fan up top for mud diver nest they will throw blade out of balance
91 GV U300 Unihome 40' Build 3811
6V92TA Detroit

Re: Replace Dometic roof AC with what?

Reply #5 –
Quote from: stump –
Check condenser fan up top for mud diver nest they will throw blade out of balance

I have found that on a couple of units.  Worst was the mud dabber one that somehow got into the inside squirrel cage.  Once on the toyhauler,  I had some vibrations, till about 2:00 AM, when the thing broke loose and came out everywhere.  Never found the entrance they used to get in and build that mud pile.

Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: Replace Dometic roof AC with what?

Reply #6 –
The more the heat attacks us, the more I like the Carriers that Brett installed.  ^.^d 

Update: DW reminded me, starting the AC early seems to cool the inside BEFORE the real heat hits.
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Replace Dometic roof AC with what?

Reply #7 –
Well, here is the latest. I ran the AC for a 1/2 hour and it ran smooth.
So, as usual, this dumbass has to see if he can find out what happened. I took off the shroud and rotated the motor shaft manually. This after watching the motor perform under power.
The motor seems to have almost 1/4" end play of the shaft! The hind end has a fan on the 4-1/4" long 1/2" diameter motor shaft while the forward 1/2" diameter by 5" long shaft has the squirrel cage fan. Only support is the motor bearings.
Never found any "foreign stuff" inside the assembly.
Only conclusion I can reach is the motor is going. It did get quite hot in the short time it ran. So hot that I couldn't touch it.
Motor specs are: Emerson Model K55HXJCP-2593  1/4HP  115V  HZ60  Amp 3.1  PH1
RPM 1650/2SPD  Thermally protected
Part #6757A313  Mfg #A89 2
Ins CL B  Air over cont  Frame 48Y
4-1/4" lg shaft  fan end  5" long shaft squirrel cage end  shaft dias are 1/2" with flat on each shaft O.D.
7.5 MFD
370 VAC
Capacitor 
I did break the squirrel cage "a bit" so a new one will be required.

Craziest thing is that this spring I did go up top and oil the motor--putting just a few drops in each oil cup on the ends of the motor housing. Guess it wasn't used to being so well cared for.

Noticed a Coleman label/sticker on the electrical connection box. Is/was the Dometic AC made by Coleman?
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: Replace Dometic roof AC with what?

Reply #8 –
If it's just a bad fan motor you should fix the unit. First try to order a new fan motor. If you can't find a new one that's affordable go to some RV places and see if they've got a junker with a good fan motor. I found a used fan motor from a junker for my old Coleman at an RV place for $35.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Replace Dometic roof AC with what?

Reply #9 –
The squirrel cage might be harder to find than the motor. Johnstone Supply is where I bought one for my '81 FT but I didn't need the squirrel cage though. They sell heating and cooling to the A/C industry.
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: Replace Dometic roof AC with what?

Reply #11 –
Just a thought: if the roof air had to be removed for "repairs", would it not be best, in the long haul, to just replace the whole unit, which puts it under warranty? I had a fridge compressor go bad, removed the whole unit, had it "re-built". Guess what? Lasted a year!  >:D
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'
 

Re: Replace Dometic roof AC with what?

Reply #12 –
My mistake---again!!
The unit is a Coleman TSR rotary 6759D series RV A/C
AND, I did find a fan motor on Amazon for $125.95 plus shipping. But, so far no luck with the blower wheel squirrel cage fan.
Lots of other size fans, but no 7" dia x 2-7/8" high x 1/2" hole x 36 blades.
So far I cannot even find the part number for the blower wheel and I have been looking since 7:00 AM this morning.
I will probably end up with a new unit if I cannot find the part.
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