Air conditioning issue

[Motor31]

I figured that this would be a good time to mention this issue as the weather is starting to warm up. Several of us have had the starter motor and capacitor burn out on the Dometic AC and ac/heatpump units that Mobile Suites uses on their rigs. I have had it happen 3 times now and once next August comes around will be out of the Dometic warranty. BTW the warranty is 3 years and the third year is parts only.

The usual situation is the AC starts to cycle. There is a loud hum and then it stops without running. It will do this several times trying to start the compressor. It usually also has a moderate to strong smell of burning insulation as electrical components are frying. If this happens shut it down ASAP as there is a good risk of fire.

What happens is the starter motor and capacitor as used by the OEM installation gets fried. The cause can be several things as I've had it happen at an RV park, a Military Fam Camp and at my Step Son's house with a separate dedicated power pole. The conditions were not the same at any one place so I can't narrow it down.

The pix show the burned units so you can see what they look like. the OEM parts numbers printed on the components are listed. (picture 1 &2)

Starter motor (small black square item) "Motor Starter WSX-5ACM"

Capacitor (cylindrical black item) "CAPACITRON #61B2D250043NNVT"

I don't know if the components can be purchased locally or not. My guess is they can from an AC supply or service center.

The info in quotes is what is printed on the OEM parts. I am not sure if that is actually the order numbers as Dometic didn't want to talk to me as a customer, they only wanted to deal with a service tech and I forgot to ask the tech that did the job for me the last time. The cost is around $65.00 for the two items from what the tech told me last November. They are common and he said they frequently fail. There are more robust parts out there that will work like those used on small residential units but Dometic won't use them. The tech said that Coleman does and their units don't fail as often as Dometics do in his experience.

The following is for informational purposes only do this at your own risk. I didn't suggest, ask, tell you to do this. I didn't sleep at a Holiday Inn Express last night or attend the Dometic service school. I just watched and took pictures as the tech did the job.

Installation is dirt simple. Step one, TURN OFF THE CIRCUIT BREAKER TO THE AC UNIT BEFORE YOU GO UP ON THE ROOF!!!!!!Remove the AC cover. ( 4 screws) Go to the small sheet metal cover over the wiring "bundle" (rats nest is more like it) and remove it. (picture 3) The 2 components are right in front and likely to be loose or flex tied to something else. There are 3 wires, just swap them to the new components. Keep in mind that a capacitor can hold a significant charge be very careful and do not touch the leads except with insulated tools. It WILL light up your life.

Assuming that the compressor and blower motor are in good shape all you have to do is close up and start the AC. While you are there it might be a good idea to clean out the fins and interior of the AC unit so it doesn't operate dirty.

I hope you enjoyed this little story and pictures.