We have a 13.5 Dometic Roof top air that the motor has gone bad. Getting some quotes now to have the motor replaced. I was wondering if this is a DIY job or if it's time to just replace the entire unit. Rear bedroom unit is same size and still running good. This one that is bad is our main living area unit. Also considering since it's 7 years old just replacing the entire unit. If I did this how hard of a job is it to DIY? Or is it better just to pay someone and have it done right? If it's plug and play then there are no worries for me to just do it myself but if it involves wiring and other stuff I will just pay to have it done.Also where is the best place to buy a new unit? And should I upgrade to a 15K roof air? Also what should I expect to pay for a new one? Any help would be appreciated..

do you have a way to get the old one off the roof? And get the new one up on the roof? Fork lift? extra help? that would be my concern.

Better check the starting capacitor before you do anything drastic. Might just be a $25 - $30 part. Unit should not be bad at 7 years.

If you are even the least bit handy and don't mind getting on top of your RV, this is definitely a do-it-yourself job and will save you several hundred dollars.If the 13,500 BTU unit was doing the job before, why go larger?Don't know best place to buy in Utah, but bought a Carrier brand 13,500 unit in Houston from PPL last week, rooftop and ceiling unit for ducted system, for $546.70, plus sales tax. 4 bolts connect the upper and lower units, then unless your rig is really old, the electrical connections are modular. One thing to make sure of is clean very well all areas where the gasket touches.Took about 1.5 hours to install. Just watch carefully as you un-install the old one, and re-install the new one the same way and you will be surprised at how easy and quickly you will finish the job.Good luck.

How much do the units weigh? I also have a bad one and was thinking of replacing with a newer model myself. If need be I can actually access a forklift if I needed it.

Replace it with a 15000 btu model. It takes two people to lift it mostly due to size but also weight & balance.

Dometic roof are motor shot. How easy to replace?

jhilley
Explorer
Jun 07, 2014
Glad to hear you got it resolved at a reasonable price. That repair quote was crazy.
dougrainer
Nomad
Jun 06, 2014
The BLACK capacitor is the comp start, the silver is the fan cap. Doug
lacofdfireman
Explorer
Jun 06, 2014
Well being that I don't have confidence in trying to diagnose my problem with this A/C unit I decided because of the fact that we need to have it ready for a trip next week that I just bought a new unit... Figured if I ended up having it diagnosed then waited for parts etc that I would be pushing it so I just decided to get a new one. Upgraded to a 15k unit and will pick it up in the morning. Contacted Dometic and they stated that this will be a direct drop in unit to replace my existing and that it would be plug and play. They also said that I didn't need to change any of the lower parts just upper only. Since my unit is ducted they said everything will work. And also that this unit will push a lot more air with less energy and is quieter than the unit I had previously. So I guess all and all this was the better way to go. Final price out the door with tax and everything was $525. My service tech wanted over $800 just to fix my old unit and $1200 to replace it. To bad I wasted an Hours worth of labor for him to diagnose the problem.. Also they said that my old analog thermostat will work with this unit. Or I could buy an upgraded digital one for $90 that would also be plug and play..
jhilley
Explorer
Jun 05, 2014
You can just short it out with a screw drive without pulling the connections.
bsinmich
Explorer
Jun 05, 2014
The reason for shorting out the capacitor is so you aren't the individual to pick it up and short it in your hands.
jhilley
Explorer
Jun 05, 2014
On your fan motor the capacitor might be mounted to the motor. Follow the brown and white leads from motor to capacitor.
lacofdfireman
Explorer
Jun 05, 2014
Thanks everyone for your help. Hopefully I will have a friend go over tonight and try a few things to see if my unit is really frozen up, ruined or what not.

I do have a few questions though. When shorting out the Capacitor to de energize it does it matter which lead you remove before you touch the 2 posts together? Also by shorting the Capacitor will it ruin the capacitor if it is still good? Reason I ask is because I want to take the capacitor off my good A/C Unit and put it onto my bad A/C unit to see if it will make the bad unit run.

Also on my A/C Unit is the Run or Fan capacitor the one next to the Hard Start capacitor? See Photo

So this is my A/C unit Serial Number and Model I guess.
jhilley
Explorer
Jun 05, 2014
This vendor on eBay has motors and shrouds at decent prices. He also has take off shrouds with blemishes for $35 that may or may not fir your AC, you have to contact him with your information.

gregory.281 on eBay
jhilley
Explorer
Jun 05, 2014
It looks like the fan motor may have a single capacitor

Connection Diagram
CG_Dawson
Explorer
Jun 05, 2014
To drain the cap. disconnect one of the leads and short it to the other, if the cap. is bad nothing will happen, if it's still got some life you will get a spark. It could be either the run or the start, or both, but since it doesn't start the start cap would be the logical choice.