Climma A/C ground fault?


Gary Wells
 

Greetings, SM 209 is trying to tease me with an intermittent trip of the master breaker.
Three air conditioners (we normally only ever run two of them simultaneously) everything aboard works fine until, for no discernable reason the master breaker will trip at either genset start or dock plug-in and not reset.
I first thought it might be a problem at the dock with stray current or bad power at the post because it had not occurred before. A few days later it did it again on genset.
I'm not sure I can explain the luck in discovering that if the blue wired leg of the forward air conditioner was disconnected from the system it solved the issue, but that's what it seems to be.
While I cannot recreate the fault on demand, I can solve it by pulling that A/C offline.
I did notice a bit of corrosion across the big (40ùf) compressor start capacitor so I changed that out. I changed out the compressor start relay a year ago. It seemed to solve it until a couple of days ago when it tripped again right upon genset start.
This morning it's at it again. I think the relay and capacitor were not players.

Any ideas on where to start with this? The unit is NOT powered on when this happens so it has to be something going into the the control box and I'm not sure where to start looking for a 0.03Amp leak. I am fairly certain it's not directly related to fan motor, compressor or temperature control 'modules' since nothing is active at the time of the trip. Maybe it's a stray chafe somewhere along that run, or some strange short at the connector block but I can't puzzle out why it only happens once in every 20 genset starts.

Thanks,

Gary W.
"Adagio", SM 209
BVI

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