A/C ? in my 357

srl520 · 05-10-2005, 02:01 PM

I purchased 93' 357 last year and it had an A/C installed by one of the prior owners. The last owner informed me that he has always had problems getting the water pump to pump water to A/C condensor. I replaced the pump with a new one after talking to the pump company (I think it was a March Pump or something like that, red in color). The pump works good if I disconnect the discharge line, there is good flow. As soon as I hook up line to A/C, the pump continues to pump, but no water makes it to A/C. I can hook up a garden hose to the suction side of pump and I get good flow to A/C and out the side of boat. Line can'nt be plugged. I am wondering if others have had my problem and how did they fix it? I was suggested that I try putting in a air releif valve. Any help will be great.

formuladude312 · 05-10-2005, 02:23 PM

I don't have A/C in my formula but i do have it in my 34' Carver, I had similar problems, Water would come in from the seacock to the strainer to the pump but would not pump thru the a/c unit and out the side of the boat, It is always when i go to commision in the spring, But i would take the hose of the discharge side of the pump (and it is a march pump) the water would flow out of the pump, Then i would put it back on and turn on the A/C and it always works, It acts like it is air bound. So whoever told you to put an air relief valve is probably correct, I also think an anti siphon valve on the discharge side between the pump and the A/C unit may also work. Make sure that the pump was installed below the water line because that could be a issue as well.

Ted G · 05-10-2005, 02:35 PM

If it's a new pump it sounds like it is mounted too high. It has to be mounted well below the waterline or it will not develop enough pressure. An air bleed can also be helpful in getting a good prime on a boat that is not kept in the water.

Poorsche · 05-10-2005, 02:58 PM

Sounds like pumps is getting air lock. That happens becuase pumps is mounted at or above water line. The water should flow from strainer up to pump up to a/c compressor/exchanger. It all has to start BELOW water line.

Mine is causing me same grief.

I put a T in water line between strainer and pump with a cut-off and a hose connection so I could flush system and run on wrk rack or trailer.

srl520 · 05-10-2005, 02:59 PM

I left out that detail. I did try mounting the pump in different locations always below the waterline. I have always had water at the pump in ea position. I did talk to a Ag pump sprayer rep and he said if it is an open system that it should not need a relief valve because as the water forces the air through the line it will exit the boat through the discharge port. This also makes sence, but something still not right. I was also told last year that if the boat is in and out of water, such as to trailor it, I am more succeptable of this problem. 1000's of boats have this same system. Someone must have a fix. I may have to get a valve just to try it.

flyby · 06-18-2005, 08:44 AM

I have a 357 and installed my own ac/heat. I went through the same stuff. My ipump is right at waterline and sometimes I have a problem getting her primed. I suck water through a ball valve/ thruhull under the motors. I used to pull the hose off of the pump until the pump primed and started pumping bigtime. Then I'd put the hose back on the pumping geyser and end getting sprayed. To fix the problem I put a tee just above the pump with a plastic ballvalve. When I start the system I just open the valve until it primes and close the valve.

The problem I have is dealing with the condesate. It currently dumps by going around the fridge and into sump under the step then it gets pumped to bilge then finally pumped out of the boat. That's not going to last.

Poorsche · 06-18-2005, 10:24 PM

My pump always worked when it was laying in bilge next to the keel--when I mounted it and made things neat-I keep getting the airlock problem. Apperntly when they say below waterline--they mean WAY below waterline.

Regards condesate--sheck out a CONDENSATER from http://www.mmair.com/product/Condensator.html -- they solve that under step condensate problem--they really work. MyA/C guy says he's installed a lot of them. The coolant water line operates a little turbo-pump that sucks up the condensate and pumps it overboard with the coolant water.

They also ahve a primer system-- http://www.mmair.com/product/Primer.html -- another great gadget.

offthefront · 06-18-2005, 10:45 PM

great info guys ...

srl520 · 06-19-2005, 12:16 AM

I had enough of trying different positions and new valve from formla. I did the same thing as flyby. I put a T in line after strainer with 3' hose going to plastic valve. If she don't prime right away, I fill the 3' line with water and she works just fine.