Today was the day to finally start the air conditioning. I'm finishing the install on a 16kbtu FCF unit. It's not happening. When I flip the breaker the fan starts and runs for about 30 seconds, then the raw water pump starts and runs (pumps a full stream overboard) for about 5 seconds, then the fan starts to slow and the breaker trips. 30 amp service, 20 amp breaker as recommended. I tried one of the other breakers and the other shore power box--same result. I guess I'll be on the phone with them tomorrow.
Finally, air conditioning...er...not so much.
- Thread starter IH82BL8
- Start date
What other loads are on that breaker? Geez, I shouldn't even answer this. But I had a problem at a slip I rented because the breaker ashore would trip if my charger and AC were going at the same time. No boat issue. Just the wiring to the shore power was limited and that, and my neighbors loads, were too much.
The A/C unit has built in safety switches that will shut down the unit if a fault is detected. These switches work independent from the power breaker to protect the unit and should not trip the breaker. The function of the breaker is to prevent fire from overheating wiring and connectors. I would say your problem is likely a wiring issue or excessive load. Sometimes the shore power cable connectors are unable to establish a good connection. You might need to test the voltage that is reaching the unit when under load. The slowing down of the fan could indicate a drop in voltage.
I used 10awg braided wiring for the install, dedicated to the A/C and a dedicated breaker. All other breakers were off during the test. Now I'm thinking I need to check the existing wiring between the shore power connection onboard and the breaker panel. It's possible that it's 12awg and needs to be upgraded to 10awg. After all this is an older boat and the builder may not have anticipated the load of an A/C unit.
The loads should never exceed 80% or so of the circuit breaker capacity. As someone suggested a clamp on ammeter would tell the story. If the AC requires more than it's rated for, check the wiring first. It could just be a bad AC unit.
If I didn't intend to use it much, I'd buy a cheap clamp on ammeter.
http://www.harborfreight.com/catalogsearch/result?q=clamp+on+meter
If I didn't intend to use it much, I'd buy a cheap clamp on ammeter.
http://www.harborfreight.com/catalogsearch/result?q=clamp+on+meter
As someone mentioned check the voltage at your unit especially on your AC starting cycle. If it is low keep going upstream until you find the problem. It could very well be contact resistance at either end of your shore power cord.
You have several several motors trying to run (compressor, pump and fan). Unlike rsistance loads such as heaters all alternating current motors take higher amperage when voltage drops.
You have several several motors trying to run (compressor, pump and fan). Unlike rsistance loads such as heaters all alternating current motors take higher amperage when voltage drops.
The symptoms are consistent with the compressor being rotor locked. It's normal for it to draw a lot of current while starting but only for a second. This won't pop the breaker. If it doesn't start to turn and keeps drawing the high current, the breaker will pop.
i would definitely measure the AC voltage during the 5 seconds the fan has slowed down. It's very common for marina voltage levels to sag under load - especially if you are at the end of a dock.
If the voltage is OK, then I'd suspect a problem with the A/C itself.
i would definitely measure the AC voltage during the 5 seconds the fan has slowed down. It's very common for marina voltage levels to sag under load - especially if you are at the end of a dock.
If the voltage is OK, then I'd suspect a problem with the A/C itself.