A/C circuit only works on Shorepower

[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.

[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.

[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.

[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.

[AC3207]

Its an automatic transfer. There is no manual switch or device. If the gen comes on it takes over if on shore power.

[bud37]

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 ?

[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.

[bud37]

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.

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.

[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

[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.