Air conditioner blows dock breaker

D

Dean Fields

New Member
Dec 14, 2020
10
Boat Info
2004 260 Searay Sundancer
Engines
350 Mercruiser w/Bravo 111 drive
What could cause the air conditioner to immediately blow the dock breaker when turned on?
 
It typically would be a bad breaker or a problem with the compressor drawing too many amps or a short to ground on the compressor. Can you run your power line to another pedestal and different dock breaker? If the other breaker pops then you probably have short to ground in the compressor which is not a repairable condition. This is easy to check as well if you have access to the front of the compressor. If no short to ground within the 3 prongs, there could be a problem with the powerboard.
 
Thank you, I have tried a different breaker and it pops it also. When you say power board are you talking about the Smx control or something on the ac unit?
 
I am afraid you are right. Thank goodness it is almost fall. The unit is almost impossible to get to.
 
I think it is interesting that the breaker on the pedestal blew and not the breaker for the AC inside the boat. Normally, the breaker on the boat would give before the higher amp breaker from the marina. This is not normal but is likely a separate issue from the AC problem itself.
 
I didn’t understand that either. The boat breaker is 15 amps, dock is 30
 
But I have tried 3 different post on the dock and it pops them all.
 
It looks like the dock circuit breakers are GFCI type which are required per code. They actually will trip at 30 milliamperes imbalance between Hot and Neutral legs for 120 volt circuits and Hot to Hot legs for 240 volt.
Seems your AC unit if that is the only thing tripping the breaker is leaking current to ground somewhere.
 
Thank you. I believe my compressor is shorted out. Do you have any other ideas of something that could be shorted?
 
You could remove the compressor wiring from the control board wiring terminals and see if the dock breaker still trips.
If this is your only HVAC unit on the boat then possibly the raw water pump also. The unit can be run for a short period of time with the RW pump disconnected. The only other thing AC powered is the switching solenoid which only operates in the heating mode. Check also the wiring to see if there is chafing to any metal parts of the unit.
It doesn't take much leakage (imbalance) to trip a GFCI.
 
Check shore power connection on the boat. Also try a different shore power cable. It does not make sense the breaker on the boat is not tripping if the AC is bad.
 
bahamabreisus said:
Check shore power connection on the boat. Also try a different shore power cable. It does not make sense the breaker on the boat is not tripping if the AC is bad.
Click to expand...
It would if the dock is a GFCI and boat is not.
The dock if a GFCI is probably a 30 amp trip on a load or short between hot and neutral but leakage to a ground or to the water will trip it at 0.030 amps. The boat's air conditioner breaker which is probably a typical 15 amp will trip only if the load or dead short exceeds 15 amps; it doesn't care if there is leakage to ground.
It seems he is only getting a trip when the air conditioner is turned on.
 
I was lucky.I found the short. It was in the orange wire from the board to the fan. All working fine now. Thanks for everyone help.
 
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