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Topic: Cant get AC to work on generator (Read 553 times) previous topic - next topic

Cant get AC to work on generator

Just got the generator running after replacing fuel lines. Runs smooth. Disconnected the shoreline to see if AC would work. No go. Seem to have power to the microwave and lights. No fuse blown. What am I missing. The magnum meter is reading 12.6 volts. Any advice appreciated.

Larry
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318

Re: Cant get AC to work on generator

Reply #1 –
Hi Larry, have you checked power at the transfer switch under the bed?

Mine has two transfer switches, one for the inverter which I removed/bypassed.
J.R.
99 U320 40' WTFE
Build # 5388

Re: Cant get AC to work on generator

Reply #2 –
Which magnum and remote do you have?

You should well over 14v with the gen running and the magnum charging.
J.R.
99 U320 40' WTFE
Build # 5388

Re: Cant get AC to work on generator

Reply #3 –
What am I looking for? How do I check? I have 2 at the foot of the bed, one going to each of the breaker boxes it appears. I turned on the refrigerator and it lit up. Inverter flashing a slow green light. Reading 13.1 V on the meter. AC works fine on 120 v..
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318

Re: Cant get AC to work on generator

Reply #4 –
If it's wired like mine, there's a 30 amp breaker in the main panel feeding the lower transfer switch, then out to the sub panel.

Have you checked all the breakers, and the reset buttons on the magnum already?
J.R.
99 U320 40' WTFE
Build # 5388

Re: Cant get AC to work on generator

Reply #5 –
Actually, thinking back the AC is not on that one as it's the inverter transfer switch.

So it would be the top one, one side is shore power input and the other is gen. Open the lid and test power with the gen on, be careful as it may be live.
J.R.
99 U320 40' WTFE
Build # 5388

Re: Cant get AC to work on generator

Reply #6 –
It sounds like you only have one hot leg instead of two.
J.R.
99 U320 40' WTFE
Build # 5388

Re: Cant get AC to work on generator

Reply #7 –
OK, just checked the breaker on the generator. It was off. Turned it on and one the bedroom AC kicked on, but only very low speed. The front one not on. Will try checking the the  power transfer box. BTW I have the ME 2515 Inverter and 2-power transfer 50's
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318

Re: Cant get AC to work on generator

Reply #8 –
Good news 120 v going into switch both legs, bad news  only coming out 1 leg.

Am I safe to assume this would be enough to not run the AC's? Will try to find a switch model to locate. Have to put the rig back into storage soon however, storms are coming.
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318

Re: Cant get AC to work on generator

Reply #9 –
When I was in a hurry I bought one at CW, they stock it.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Cant get AC to work on generator

Reply #10 –
That's better then a generator problem though:) Glad you found it Larry!

Yes, there's one AC on each leg and the contacts in the transfer switch aren't making a good clean/solid connection. I believe there's a few members that have also repaired them too, or replaced the contacts.

You could do some rewiring and use the inverter transfer switch since your inverter has pass through capabilities.

J.R.
99 U320 40' WTFE
Build # 5388

Re: Cant get AC to work on generator

Reply #11 –
With only one leg hot (hot= 120 VAC +/- 10% between each hot and the neutral  (white), ONLY those circuits on the "good one" will run at all, and should run at regular speed. 

Low speed could indicate low voltage which could damage the appliance. SO, CHECK VOLTAGE. 
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Cant get AC to work on generator

Reply #12 –
Quote from: ohsonew –
Good news 120 v going into switch both legs, bad news  only coming out 1 leg.

Am I safe to assume this would be enough to not run the AC's? Will try to find a switch model to locate. Have to put the rig back into storage soon however, storms are coming.

The older generators were wired to only put out 120V so if you checked each phase while on generator you would get 120v to neutral/ground.  If you checked between the phases you will get 0V since they both are the same phase.  Now if you shut down generator and plug into 50 a plug you will still get the 120v to ground/neutral  and will get 240V between the phases.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Cant get AC to work on generator

Reply #13 –
Thanks for the advice and help everyone. When I checked the voltage to the ground, both incoming and 1 outgoing leg was at 120 volts. I will be researching this week on what to do for a replacement. Won't see the coach till at least this weekend.

Larry
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318
 

Re: Cant get AC to work on generator

Reply #14 –
Just ordered a new power transformer contactor part #CR353ADY39A from Galco.com. It should arrive by Tuesday via UPS ground. I ordered via the phone line, very good customer service rep. Here is the good thing, only $32.56 plus shipping. No tax since I'm out of Michigan. Most other places I checked wanted from $125-150. If you need &/or want a spare this price can't be beat. I'll report back when it is installed.

Larry
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318