Troubleshooting AC pump - won't start after clogged sea strainer

My experience with a similiar set up is that the pump will prime by removing the bleed screw. My pump is turned on by demand from atleast one unit. Beyond this I can’t help.

Yes I would give that a try. I have a separate breaker for the pump with an LED light. I turn the pump on first and then flip breakers for each AC unit I want to run. I have the SMX 2 controls and it is not at all uncommon for a unit to turn on by just turning the breaker on. Not requiring me to ask for cool on the control panel.

Welcome to boating in Florida. If your sea strainer was that badly clogged, then your intake and out flow hoses are probably clogged also.

First of all, if the pump doesn’t start as in the motor doesn’t turn then it is not a priming issue. Don’t waste time trying to prime it.

you need to know whether or not the pump runs at all time or whether it runs only when a compressor starts. First you said it was always on as long as the pump breaker is on then you said you re not sure

trace the power from the pump back and see if it goes into a relay box aka triacs. If so, then one of the unit needs to be in cooling mode for the pump to run

If you don’t see any relay box and the power comes straight from the breaker then check for power at the pump but it’s likely a problem with the pump.

strainer cleaning frequency depends on location in Florida. Some places are worst than others, sometimes it varies from one end of a pier to the other. Personally I m a big fan of external South Bay strainer. No more clogged strainer, you just need to make sure your diver scrubs them every month.

in SoFl and maybe elsewhere we re having an issue with small white mussel shells, about 1/3” that growths inside hoses and coils. They get loose and clog manifold and fittings. That’s a frequent cause of issues.

No you shouldn’t have to disassemble the pump head to clean it.

I have seen this needed on Magnetic drive pumps. But not on shaft driven pumps.

You could have a bad trigger on the salon AC which would explain why it only started when you turned on another unit

the pump shouldn’t loose prime unless you open the strainer.

I have had the exact situation that Pascal is referring to. Becomes more difficult to troubleshoot when you have multiple units running off 1 pump at the same time. Then the unit with the bad trigger will be very intermittent as the other 2 units are demanding water at the same time that the unit with the bad trigger needs water thus masking the fault.

I have never understood why AC manufacturers don’t put a **** override switch on their relay boxes so you can just start the pump to troubleshoot it without having to trigger HPFs… duh!

You can test the triggers with a multimeter.

Of course but I was talking about troubleshooting the pump. Priming issue, flow issue etc

Yeah, if the pump is 2 years old or more, it's most likely the pump. I generally only get 2-3 years out of any sea water pump unless it's a march with a magnetic end.

If you have a Brass/Bronze pump you may want to check the impeller on the pump.
Last summer on the hottest day all three A/C units went off on high pressure. Further investigation revealed the pump. 1/2 HP 230/1/60 was not outputting much water from the two above water thru hulls. After checking strainer (clean) and prime ( it was primed) pump was pulled out. After disassembling the front cover we discovered to brass/bronze impeller has worn down to approximately half its original size. See picture for comparison. Luckily our local marine wholesaler (shout out to John at Midwest Marine Supply in St. Clair Shores. MI) had a brand new Oberdorfer pump and motor in stock. Not cheap, ouch. Re-installed and Voila all air units started up and function like new. Checking with previous owner he had not done any service to the pump. As a precaution, a rebuild kit for pump and new motor are ready for service as a backup. Like most problems on large boats keep your eyes, ears and wallet open.

Problem is that usually you also have erosion on the pump housing so while a new impeller will help the pump will still not pump what it should. Even worst sometimes the housing develops a pin hole.

I ll never use a bronze head pump ever again

In New Jersey also, I've had little black mussels get inside from the clam shell on the bottom of the boat thru the line and into the fittings before the strainer and pump. Restricting water flow.