Problem running 2nd a.c on generator

ctwebb wrote:
now it sounds like the Transfer switch is opening when starting the second unit.

Monitor the voltage on this leg as the A/C starts. Not sure what the cut-off would be but the relay will drop out if voltage does sag too much.

Try swapping the air conditioners each to the other side of the breaker panel. This will help determine if you have a problem A/C or if you have a wiring issue.

Check the transfer switch sensor wire is connected to the side where the A/C actually runs. s/b on the 30 amp side.

Could temporarily bypass the transfer switch.

Could wire the transfer switch to have the NC side on the generator but that would not be the preferred position.

ctwebb wrote:
It is a 50 amp service , Sorry I should have been more informative.

Then with a 50 amp transfer box, the genset should have had the 30 amp genset breaker on the 50 leg input of the transfer box that supplies the MAIN AC. The 20 amp breaker on the genset should have been to the other line input of the transfer box. I hope the dealership did not miswire at the Transfer box, but they may have. You also need to make sure at the Genset, where it connects to the 120 wiring to the transfer box, it DOES have 4 wires---Black/Red/White/Green. I would hope the RV maker wired the genset compartment for a 50 amp(4 wires instead of 3 ) supply. Doug

It is a 50 amp service , Sorry I should have been more informative.

I have an Onan 5.5 and yes. I do from time to time trip a breaker when Running A/Cs but.. Normally that 50 amp (5500 watt) genny can deliver "All I can eat"

That's 2 A/Cs. The Water heater,, Fridge and a fairly impressive bunch of electronics including a 100 watt Radio transmitter (PEP) though it runs on 12, well 13.6 volts. But that is supplied by the Progressive Dynamics 9180+wizard so even it eats off the generator.

I've also powered a 2nd RV or a ham radio Field day operation with it at the same time.

One thought.... And it happened again this spring... I parked in the cotton woods during cottonwood season.. So naturally the condenser's on the A/C's had a nice "Blanket" of cottonwood cotton on them.. Sure enough they started tripping their 20 amp branch circuits.. Since my front unit is a Coleman and my Rear an ADVENT AIR with a Coleman fan on the condenser end of the motor shaft I removed the outer covers, pealed or blew off the cotton, put the covers back on (4 bolts on teh coleman 10 screws on the advent) and all was right with the world.

NOTE: most A/Cs it's not that easy (you need to remove an inner cover as well but Colemans' BLOW, not suck so the cotton is on the OUTSIDE of the condenser. Very nice.

A 4k Onan will run 2 AC units, but be at its limit. A 5.5K Onan has 1500 watts to spare. You ALWAYS run the 2nd AC from the 2nd breaker on the Onan. Now, it seems between you and the dealer, the Onan feed wiring is NOT correct. You moved to the other breaker but if NOT wired correctly, will not work correctly as you found out. The MAIN Onan breaker should feed the Auto Transfer Box. The 2nd breaker should feed the 2nd AC. UNLESS you have 50 amp service. You need to state which service you have---- 30 or 50 amp. That makes a difference in how the Onan wiring is set up. Doug

Yes it should but not much else. Are the hot water heater and refrigerator on propane? Have you tried starting the second AC 30 minutes after being on generator...time enough for the converter/battery charger to draw fewer amps?

With all other loads off and you still have this problem...two hard start kits may be in your future.