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

MD - Glad you've got it!

Bryan's not only got you running! With this knowledge you'll make sure the twist lock is FULLY seated, EVERY time, and that'll keep you from having early failure in those contacts.

carringb wrote:
Also if you have a twist-lock cord on the mothorhome, make sure its it is actually turned after the cord is inserted, before tightening the retainer ring. Otherwise the twist lock contacts won't have proper engagement.

We have a winner! Since I've lost most of the use of my hands I have not been the one connecting the electricity. There is a slight clockwise twist to secure the power supply cable to the RV. My brother-in-law twisted it in for me and connected the power cable to a 20 amp outlet at the RV barn. It ran for 15 minutes beautifully. I am still taking it to my RV repair shop to get a Maxxair cover and a black tank flush installed. But the mystery of the air conditioner that works on generator but not shore power has been solved.

Many thanks to all of you who offered your expertise to get this poor old disabled vet back on the road!

KAttkisson wrote:
please inform us what is found as this is intriguing. Thanks

WILCO. And I won't do anything unsafe. Heading to trusted RV repair shop next week, then to nearest Thor dealer in New Braunfels if necessary.

please inform us what is found as this is intriguing. Thanks

Find all GFI 110vac outlets and press reset buttons. Go to power panel and open and close all circuit breakers. Look at shore power plug, check for loose wires. If none of these are the culprit, find an RV repair place that does RV 110vac troubleshooting and repairs or an electrician. Don't risk your life.

Thanks for all the responses. The a/c works on the propane generator but not 30 amp. Both the 30 amp outlet and the 30 amp cord from the outlet to the rv test out fine. There are no appliances on at the same time except the refrigerator and some lcd lights. We haven't tried the on-demand water heater yet. I will double check the twist connection, though we've had that on the previous two rvs with no problems. Guess I call Thor tomorrow.

Could be low voltage, it has to be tested under conditions that represent the problem load.

I plug an AC voltmeter into one of my interior outlets, monitor readings under various loads. While it is not the same circuit as the air conditioner, it provides a good clue as to what is going on between the breaker box and the power source (measuring at the source usually just tells me no-load voltage).

I want to see at least 108 V inside when running the high loads (nominal is 120 V), no more than 132 V with no load. I also want to see only a small drop from post to inside under load, as large voltage drop suggests a high-resistance connection somewhere: socket or plug, cord connections at junction box, connections inside breaker box, too much cord too small. Problem connection can be either live or neutral. High resistance connections often don't show up with no-load voltage readings, or even light loads.

I'm a little confused. I think you are saying that the compressor won't start on either shore power or generator? If this is correct you probably have a bad start capacitor allowing the internal overload to trip.

If it will run on the generator and not on shore power everything else being brought up in replies need to be investigated.

Also if you have a twist-lock cord on the mothorhome, make sure its it is actually turned after the cord is inserted, before tightening the retainer ring. Otherwise the twist lock contacts won't have proper engagement.

Major DAD, It seems you have ruled out the usual suspects and as noted the problem is perplexing as it is the opposite of the normal complaint.

I am not HVAC knowledgeable, so I am assuming that the AC unit does not have a auto reset CB on the circuit from the panel to the unit and that is none inside the unit, so that leaves the line from the shoreline connection to the output of the transfer switch. That of course is assuming there is a transfer switch.

If you have a shoreline that has to be disconnected from the 30 amp outlet and connected to an outlet in the service bay, then the wiring from that outlet to the CB panel needs to be tested.

There is a guy on here that has Golden in his forum user name who is a really knowledgeable HVAC guy, in fact it is/was his profession. Try searching for him. Also Chris Bryant is an outstanding source of knowledge.

Good luck with your problem and sorry to read about the reason you downsized. It just so happens that we are doing the same thing for the same reasons.