Post edited 3:56 pm – September 4, 2011 by deerow

I have 3 self contained Marine Air Systems.  One has its own water pump (this unit appears to have both the unit and the water pump on one breaker).  Two share a water pump and I have located a unit that appears to be a pump relay box (2 PRP).  The AC units are not used unless we spend the night on the boat which hasn't happened since the 1st of the year (reverse cycle for heat!).  

Last Tuesday, lightning struck a tree across the canal approx. 80' from the boat.  The shore power breakers tripped but nothing else appears to be damaged.  I'm not sure if this has anything to do with the AC problem.  The pump that services two units is on one breaker, and each AC unit has it own breaker.  When I turn on the pump breaker, the pump hums.  When I turn on the AC units, I can no longer hear the humming over the noise of the AC units, however, I have no water flow. I removed the hose from the output of the pump and have water flowing (it's below the waterline) so I know that there is no blockage in the line.  

What's the best way to determine whether the pump or the relay is bad?

Steve,

After my initial post, I checked the output from the relay.  It was always 47 volts whether the AC was on or not.  I bypassed the relay by connecting the pump leads directly to the power terminal in the relay.  So now the pump runs when the breaker is turned on.  The pump runs great!  I'll need to check to see how much the pump is drawing.  I'm not sure what make and model the pump is because I can't get close enough to it to read any labels.  I'll try using a digital camera to take a picture of the label.

Thanks for your help,

Mark