MBS Diesel Gen "short circuit" error

[ericlakin]

I have the 3.2KW diesel gen in my Sunseeker 2400R. I occasionally get a "Short Circuit" error on the Cummins Onan display when the AC compressor starts up, resulting in generator shutdown. The dealer looked at it last year and said a wire was loose in the AC unit and it seemed to be fine since. This past week it gave the error again right when the AC compressor started up, but with subsequent tests I could not reproduce the error. Nothing else was running. Fridge was off. Microwave was off. Not on shore power. MBS engine not running. Not extremely hot outside.

I have read that switching to an Atwood AC unit results in less load on the generator. Not sure how difficult that switch would be nor the cost. If we keep this little MBS for a while I might look into that. Has anyone done this sort of switch recently? There have been some similar posts but they are so old I could not reply to them to get the conversation going.

[SeaDog]

The compressors in these roof top AC are not really different from each other one may draw an amp or more but for the most part are identical. Replacing an AC can be expensive if you can't do it yourself. You might consider adding a hard start kit someone like the SPP6 and see if the doesn't solve the problem. Also check all the connections and ensure they are tight both AC and your stat

[Rich.M]

Have you tried adding the dometic start capacitor. I had the same issue with the diesel generator , adding the start capacitor resolved it.

[ericlakin]

Is there any chance you might have the part number for that capacitor?

[Rich.M]

Sorry, I'm not at home to look it up. We are in Mesa verde for the next 3 days. Currently halfway thru our trip to the four corners. I do remember that 2 capacitors are listed . Your part depends on the serial number of your unit. Go on a ladder on the passenger side and take of the plastic cover off. ( 4 screws) the serial number may be listed inside or in the square metal box. Open the electrical box and confirm no start cap. The wiring diagram is inside. There are utube videos on adding start caps if you need a guide. I found the part number needed by my unit was on the dometic website somewhere. Once I knew the part number then bought on Amazon. Very easy to put in. Used a large zip tie to anchor it in the electrical box. Good luck.

[KatanaPilot]

Originally Posted by ericlakin

I have the 3.2KW diesel gen in my Sunseeker 2400R. I occasionally get a "Short Circuit" error on the Cummins Onan display when the AC compressor starts up, resulting in generator shutdown. The dealer looked at it last year and said a wire was loose in the AC unit and it seemed to be fine since. This past week it gave the error again right when the AC compressor started up, but with subsequent tests I could not reproduce the error. Nothing else was running. Fridge was off. Microwave was off. Not on shore power. MBS engine not running. Not extremely hot outside.

I have read that switching to an Atwood AC unit results in less load on the generator. Not sure how difficult that switch would be nor the cost. If we keep this little MBS for a while I might look into that. Has anyone done this sort of switch recently? There have been some similar posts but they are so old I could not reply to them to get the conversation going.

We were fed up with the noise level of the Dometic 13.5K A/C and the hard starting of that unit on our Forester MBS. We also have the Cummins/Onan 3.2KW diesel generator. I installed an Atwood 15K BTU heat pump and it works great. Cooling is better, noise level is much less and there are three noticeably different fan speeds. The diesel generator starts the Atwood with no issues even with the converter charging on high.

The install took me the better part of a day, as I am not an experienced RV tech. I have a forklift and a scissor lift which made getting the A/C off and on the roof doable by one person. Obviously without that kind of equipment, the job is not easy. The inside work was straightforward once I figured out the wiring differences for the Atwood thermostat.

It's not an inexpensive mod, but the Atwood was on sale at PPL Motorhomes when we bought. For us, the expense was worthwhile given the lower noise, better cooling (and heat function too) and lower load on generator.

[ericlakin]

Well I wish we lived close together, because I'd grab some steaks and some beer and bring my MBS over for an afternoon!

Originally Posted by Rich.M

Have you tried adding the dometic start capacitor. I had the same issue with the diesel generator , adding the start capacitor resolved it.

Originally Posted by KatanaPilot

We were fed up with the noise level of the Dometic 13.5K A/C and the hard starting of that unit on our Forester MBS. We also have the Cummins/Onan 3.2KW diesel generator. I installed an Atwood 15K BTU heat pump and it works great. Cooling is better, noise level is much less and there are three noticeably different fan speeds. The diesel generator starts the Atwood with no issues even with the converter charging on high.

The install took me the better part of a day, as I am not an experienced RV tech. I have a forklift and a scissor lift which made getting the A/C off and on the roof doable by one person. Obviously without that kind of equipment, the job is not easy. The inside work was straightforward once I figured out the wiring differences for the Atwood thermostat.

It's not an inexpensive mod, but the Atwood was on sale at PPL Motorhomes when we bought. For us, the expense was worthwhile given the lower noise, better cooling (and heat function too) and lower load on generator.

[KatanaPilot]

Originally Posted by ericlakin

Well I wish we lived close together, because I'd grab some steaks and some beer and bring my MBS over for an afternoon!

Thanks for the offer, sorry we are so far away.