dual rooftop air conditioning wiring problems

[johnnytugs1]

Happy Independence Day to you all! I'm trying to help out my brother in law with his a/c issues. When plugged in to shore power (land) the foward a/c unit works and not the aft unit. when running off the genset only the aft (rear) a/c unit works. there is an a/c selector switch that has one unit aft and to run both units switch to forward. when running off genset the forward doesn't work and on land the aft unit doesn't work, any suggestions?
Thanks,
John

[circleD]

It could be a PO wiring job or an addition put on there and it was wired up to run off of the bigger of the two powers or easiest to get to. Do you have a 30 amp plug or 50? Is it wired 50 amps?

[Stripe]

Nope, that is standard on the RV, one unit works off strictly GEN t'uther off the shore power..  A lot of the older rigs were wired up that way, including my old '77 Coachmen..

[circleD]

I can switch from front to rear A/C and they run off of either power.  i??

[DaveVA78Chieftain]

There should be a switch for both when running of generator.
On shore power you can only run one at a time.
Has to do with available amperage.
On shore power you only have 30 amps available of which 20 are reserved for a single AC unit.
On genny (6.5KW) you have a 30 amp leg and a 25 amp leg (55 amps total available).  The 30 amp is used to support all the items used on the shore power leg and the 25 amp leg is used to support the extra AC.

Dave

[pvoth1111]

I rewired mine to work off 50 amp service.....both a/c's blowing right now...its cold in here....

there should be a switch to let you run front one or back one.....and both off generator.....maybe over fridge...that's where my switch is...( no longer used )

[johnnytugs1]

Thanks very much to you all, I will look into it a little further. I'll check that switch out and see if it's messed up. You guys rock!
John

[MotorPro]

Do you have the power cord pluged into the gen outlet when you have the gen on?