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Roof A/C fan motor replacement

Yahoo Message Number: 74026
Need roof A/C fan motor replacement procedure and degree of difficulty for DIY. Also need sources for fan motor.
Symptoms: Fan runs for a few minutes then begins to intermitantlty chatter. Then, RPM bogs down and fan motor stops. This happens whether the control is set for "COOL" or "FAN". While the fan is running with the control set at "COOL", the refrigeration unit is puting out adequate cool air.
A tech advised that I probably need to replace the fan motor. He estimated 2 to 3 hours labor plus $100 to $160 for the motor. I remember someone discussing a fan motor replacement but, my search of the archives did not reveal any results. The A/C is a Dometic combo A/C, Heat Pump Model #630215.321 original factory installed unit. The motor is an AO Smith Model #F42C02A61, 1/4 HP, 1650 RPM, 3.3 Amp.

Qustions:

Has anyone done this replacement? What is the degree of difficulty? I am a fair mechanic but, I have never done this before. Will I need any special tools? What is the procedure? Any pitfalls?

Or....should I let the certified tech do the job?

Daron Hairabedian, 98 Allure 30226.

Re: Roof A/C fan motor replacement

Reply #1 –
Yahoo Message Number: 74027
I forgot to mention that I pulled the covers and inpected to see if the fan squirrel cages were interfering with the housing. They seemed to rotate freely. The coil vanes and all enlse inside is clean.
Daron

Re: Roof A/C fan motor replacement

Reply #2 –
Yahoo Message Number: 74036
Check first that the fan hasn't just 'thrown' a balance weight - this will cause the imbalance and chatter
Techie who came to service ours the other day commented that the clip on balance weights need keeping an eye on - they will throw themselves off if not occasionally pushed back into place

Ian S.

2005 Allure #32321

Re: Roof A/C fan motor replacement

Reply #3 –
Yahoo Message Number: 74048
I had the squirrel cage warp and jam into the housing. Replaced the cage in an Elk's parking lot in about 2 hours. Had to take the motor loose to remove the cage. There is another fan on the other end of the motor. Didn't consider it a difficult job. Had to disassemble the sheet metal shroud around the cage. Only issue was it was July in Texarkana and hotter n blazes!!

Judy n Joe

98 Intrigue 10578

Re: Roof A/C fan motor replacement

Reply #4 –
Yahoo Message Number: 74050
Must have been on the Arkansas side of the line...

buck

k7wn, '99magna5653, Cat C10, Allison HD4060, SantaFe toad

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Re: Roof A/C fan motor replacement

Reply #5 –
Yahoo Message Number: 74072
Friend I have a 99 Allure, Last spring in Yuma I orderd from Dometic Two Fan Motor Bushing kits. Around six dollars each but 15 dollars for shipping Min. charge. Being in the Repair Biz in my other life I always orderd OEM Parts. The A/C runs quiet now. They dont make Comprssor Mount Bushings for our Model. Turns out it was just Fan Motor bushings. Get Your Model and S/N of your unit handy and Call Dometic, Google Dometic for phone number. I would order a motor from them and Capicator but Granger most likly can help you out. Working for Cat I always used them on Fuel Daytank Pumps Have you motor and Capicator number ready Also call them. Google Granger and check out on line Catalog. Im sure you can find a way to buy from them as they are wholesale only. Just say you work at a Biz. then Pay Tax and Cash or credit card. They also can ship to you. Hope this helps Ken 99 Allure 30356

Re: Roof A/C fan motor replacement- Follow up

Reply #6 –
Yahoo Message Number: 74756
Job: Replace a failed fan motor on a Duo Therm/ Dometic Penguin roof air conditioner, 1998 vintage.
This is for anyone who may need to do this job in the future. I received very little advice so, I went ahead on my own.

1. I found an A O Smith A/C motor with both squirrel cage fans attached at Northwest RV, Eugene, OR for $99. It appeared to be new/unused. However the mounting system was different than my original.
2. The sheet metal rear fan shroud had to be disassembled in order to remove the old motor and fan. This entailed removing several sheet metal screws and bending back the swaged assembly tabs to pull it apart and remove it from the A/C base plate. Care must be exercised at this point to avoid damage to the adjacent Knife edged cooling vanes....and your knuckles and forearms. I lost a little skin here before I decided to cover the vanes with shop towels.
3. Adapting the new motor to be able to use the original mounting brackets was time consuming but, doable. The shaft lengths, squirrel cage fans and clearances were all OK.
4. The front squirrel cage fan could not be removed from it's shroud without extensive additional work due to the lack of clearance. If there is a trick to this , I could not figure it out. The fan seemed to be in good condition so I left it allone and attached it to the shaft of the new motor. The only difference is that the new fan is galvanized steel and the old one is high strength plastic.
5. I re-attached all of the electrical wires to the same connections using the original motor's color coding system.
6. Tested the operation. All OK except for one detail.
7. Re-installed all sheet metal covers and applied new foam vibration dampening foam strips. Then I re-installed the ABS plastic cover.

What is the one problem detail, you say? Here is where I need the help of one of you electrical Gurus. I seem to have one electrical in compatibility. When activated the motor runs only at "HIGH" speed no matter what the setting on the control center.

Any Ideas as to how I can track this down and correct it?

Daron .

Re: Roof A/C fan motor replacement- Follow up

Reply #7 –
Yahoo Message Number: 74770
Thanks for sharing, Last year I orderd from new Dometic fan motor mounting bushing kits for each A/C from them. Easy change out and runs quit. Never changed the motor yet. Did you get a new Capicator with the motor? Should be changed with the motor. Does the replacmenbt motor have the same number of wires as the original? Sometimes to motor maker will have the same number of wires for different fan speeds and the colors are the same but miscolored compaird to O.E.M. Sounds like you got a great deal, If it were me I woud of paid the extra money and orderd it from Dometic. BTW I Yearly oil our motors! They do have lifetime bearings but do it anyway. Being in your shoes I would bypass the Dometic control and direct connect the 120 volt power to test the motor and see if by connecting to the correct color wires you get different speeds like a bench test. Please keep us posted! Our 12 year old Allure I too worry when the Failure will occur on out Dometic Fan Motors. You have to have a place to start. If you are able to get different speeds then go from there. The neat thing is you have a sister A/C to compare to. Ken 99 Allure 30356

Re: Roof A/C fan motor replacement- Follow up

Reply #8 –
Yahoo Message Number: 74789
Ken,

Thanks for your response. I was beginning to get a little lonely on this project! No, I did not get a new capacitor. Good idea. I will purchase one from Dometic or another parts source and install it asap. I have never replaced one. Is it a simple plug-in or is wiring involved? Do you know a good source or should I just buy from a local RV supply store?
I am proud that I was able to retrofit the new motor to the original mounts. However, In retrospect I agree with you; it would have been better to buy the OEM direct replacement motor. But, now I am committed after investing so much time and effort!
Yes, the new motor has the same number of wires as the original. Both the new and old had one wire stubbed (dead). However the new motor had a different color stubbed. When I was re-connecting the wires, It did not seem logical to connect a yellow to a red so, I disregarded that and connected wire matching according to the original motor colors. That may be the problem pair of wires. I think you are right regarding the OEM miscolered wires on the new motor.
You made a good suggestion. I did not think about comparing the wiring to the sister air conditioner in the rear of the coach. It is not the original like the 13 year old that I am working on. The entire unit was replaced about five years ago. Nonetheless, examination of the wiring on that unit may yield a few clues.
If that does not help, I will try your bench test suggestion. I will probably be able to investigate within about two weeks. Meanwhile, we have air, albeit high power fan only. Noisy but, welcome when it gets real hot inside!
As a devout tinkerer, I can not give up now as it has become a personal challenge. I like to consider this project as a "learning opportunity".
As in many of my projects, so far I have learned a few things...... not to do!

Daron Hairabedian, 98 Allure, 30226

Re: Roof A/C fan motor replacement- Follow up

Reply #9 –
Yahoo Message Number: 74809
Hi Friend, Most likly you can purchase a Capaciter locally, You must copy the Volt ratings and the unit of Capaciter in Farids and have a close match. Most likly you can live with your old one. Keep us posted on findings. No wiring is neaded just R&R. Ken 99 Allure 30356