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A/C circuit only works on Shorepower
Posted: June 24th, 2025, 1:20 pm
by AC3207
1986 AC3207 with a Kohler 7.5 gen. generator. Circuit 1 has plugs/misc and Circuit 2 has 2 AC units. Was cruising last summer with generator on and both AC units running and Circuit 2 lost power. Reset breaker no difference. got back to dock and shore power powered up circuit 2 fine. I have looked for circuit breakers on the generator itself and could not find any. Currently thinking maybe I should change the main circuit 2 breaker? Thoughts? Thanks.
Re: A/C circuit only works on Shorepower
Posted: June 25th, 2025, 2:28 pm
by km1125
I believe there should be a breaker at the generator.
Do you have a manual shore/generator switch? You probably should inspect the wiring on that (with power disconnected!) to see if there's anything wrong, like loose or corroded connections.
Re: A/C circuit only works on Shorepower
Posted: June 25th, 2025, 7:39 pm
by AC3207
I have not been able to find any circuit breakers on the generator or in the manual. Its a Kohler 7.5R27, would the generator breakers be in a separate location from the gen or the main panel? I have pulled the panel and looked at the Main breaker for circuit 2. Its a 3 slot (not sure what you really call it) breaker with the switch in the middle, in the photo its has the three yellow stickers it. I have searched online and cannot find similar breakers with three slots like this one. I may be confused on them being one piece. They have a screw that runs through them and holds them together. See photos.

Re: A/C circuit only works on Shorepower
Posted: June 26th, 2025, 11:26 am
by km1125
The main "3 slot (not sure what you really call it) breaker with the switch in the middle" is a reverse-polarity-sensing breaker which will trip (or not engage) if it senses a reverse-polarity issue.
What do you use to switch from generator power to shore power? Is it automatic or do you have some kind of manual switch?
I don't know that generator model, but several models will have their main breaker in a different spot than the controls. I just quickly looked at a manual for that genset online and don't see any indications of it having a breaker on the generator.
If the generator is still supplying power to circuit #1 while circuit #2 is out, then it wouldn't be a main breaker on the generator. The problem would be wherever you switch from shore power to genset power. That could be a manual switch or it could be some automatic relays.
Re: A/C circuit only works on Shorepower
Posted: June 28th, 2025, 1:51 am
by AC3207
Its an automatic transfer. There is no manual switch or device. If the gen comes on it takes over if on shore power.
Re: A/C circuit only works on Shorepower
Posted: June 28th, 2025, 6:58 am
by bud37
AC3207 wrote:Source of the post Its an automatic transfer. There is no manual switch or device. If the gen comes on it takes over if on shore power.
I don't think you have said but does the generator power up anything at all now ?
If it is automatic then there should/may be a transfer switch, when the generator was powering up both sides #1 and #2 did you hear a clicking sound when the generator was taking over that you don't hear now ?
Re: A/C circuit only works on Shorepower
Posted: June 28th, 2025, 9:47 am
by AC3207
Yes the gen powers circuit 1 fine. It just doesnt show any voltage on circuit 2 nor does anything power up on circuit 2. Everything works on shore power.
Re: A/C circuit only works on Shorepower
Posted: June 28th, 2025, 5:44 pm
by bud37
AC3207 wrote:Source of the post Yes the gen powers circuit 1 fine. It just doesnt show any voltage on circuit 2 nor does anything power up on circuit 2. Everything works on shore power.
AC3207 wrote:Source of the post Its an automatic transfer. There is no manual switch or device. If the gen comes on it takes over if on shore power.
I believe there has to be something that isolates the boat when the gen is on and connected to shore IMO.
Re: A/C circuit only works on Shorepower
Posted: June 28th, 2025, 6:32 pm
by buster53
Here are my thoughts FWIW, my boat does have an automatic transfer switch and you can hear a chatter when the switch does its thing, switching from shore to genset or back to shore. All automatic, I don’t have to do a thing, but I do have a somewhat newer Carver where the auto switches are standard equipment. Older Carver’s like the OP’s as well as the late 80’s 3807 I used to have all have manual switches. Maybe the auto switch was an option back in the 80’s or maybe a PO made the change himself
Re: A/C circuit only works on Shorepower
Posted: June 28th, 2025, 6:48 pm
by km1125
Yea, the 356's have a separate auto transfer switch behind the main electrical panel.
I believe the OP has the genset with an auto-transfer function. I did see some wiring info in the manual about that, but not enough info on exactly where the relays were located. There should be two sets of relays - one for "Circuit 1" and one for "Circuit 2" (similar to how the 356 is setup). I'd bet the one relay for "Circuit 2" has burned contacts.