2017 Thor Compass a/c works on generator but not 30 amp

carringb wrote:
I actually run my A/C off a 15 amp circuit no problem

Actually I am right with you on this. My a/c runs off 15 amp service just fine at home. I was only trying to rule out the possibility given we are not familiar with his particular rig.

Then there is the unknown condition of the power being provided where he is staying....hence your comment about measuring voltage.
Right On carringb. His problem might go away when staying somewhere else, maybe as simple as changing campsites to one closer to the campground power source.

X2 on making sure other electrical is off, such as electric water heating. I had a mystery draw that turned out to be a water hot pot that had been accidentally switched on!

30 amp circuit should run that just fine. I actually run my A/C off a 15amp circuit no problem. If 30 won't start it, you should monitor voltage in the coach when it tries to start, and see if its dropping below 110 volts during startup.

j-d is onto something. You were not clear that you have the following condition. Make sure you use a 30A power cord all the way to the campsite power box. If it is too short, use a 30A extension cord. Do NOT convert to a 20A cord. Menards sells 25 foot long 30A extension cords cheap. Even with a 30A extension cord, it can become questionable with certain rigs.

Another culprit could be your power transfer switch, assumed you have one. It could be faulty.

One more thought. Is there any other appliance in the motor home that could be turned to the "on" position? Something like a simple hair drier plugged into a shore-power-only outlet will rob the power to the a/c unit stealing the thunder it takes to get it going.

You do have a 2017 model. I assume you are under warranty. I would call the RV manufacture Thor Industries. Hopefully they can offer you some trouble-shooting tips while you are on your trip, rather than saying to take it in at your next opportunity.

BTW: I see Thor installed a 68 pound, 16 gallon propane tank inside that diesel Transit. Unless special ordered with a diesel generator, Sprinter & Transit diesels generally come with a propane generator. Nice to see you have great reserves.

Our 40 pound, 10 gallon propane tank serves us very well, but it supports only the fridge, stove, hot water tank and furnace. We have a gasoline generator utilizing a 55 gallon E350 fuel tank.

First, must say that your case is the opposite of just about all others. Usually, A/C will start on 30A shore tie and it's the owner's generator that won't start it.

It seems to me that your household power outlet is deficient somewhere. You could have a 30A receptacle connected to a 30A branch circuit in a fully good 200A power center in the house. But if the connecting WIRE isn't rated for 30A (too small a wire gauge), your A/C will not be able to draw the power it needs.

Likewise, if your outlet is OK but you extend the RV's shore tie cable with a light duty extension cord, the A/C's starting demand won't be met.

Look at it this way: Your garden hose and the city water main out in the street might measure 75-PSI water pressure. That does NOT mean your hose can deliver anywhere near the gallonage that the main can. You can have voltage, but that doesn't mean you're going to get the amperage you need.

Do you have an AC (alternating current) voltmeter that you can set up in the coach and see what happens to voltage when you try to start A/C on shore tie? My guess is it's going to take a nosedive.

Harvard wrote:
Are there any breakers involved in this "shut down"? If so, which breaker?

Good question...but no breakers trip. The compressor tries to start, then shuts down. If you try to start it again, the same thing happens. The blower isn't affected.

Are there any breakers involved in this "shut down"? If so, which breaker?