Marine AC not pumping water

[photo-dude]

I just bought a 1987 Hunter 31 and the AC worked before having it hauled to do a bottom job on it last week. When I turned it on tonight, it ran and cooled for about 2 minutes and then tripped the breaker.... no water being discharged overboard.

I have been told that it's probably lost prime when it was hauled. The problem is that I'm a brand new boat owner and brand new to boats larger than a kayak. I haven't had any luck finding a plumbing diagram for the unit so I can see where the strainer is, the pump and discharge hose, etc. I'm on a real slow internet connection at the marina and haven't been able to download any manuals (large PDF files).

Can anyone out there offer any advise?

 

[Ted]

Locate your through hull fittings and one by one follow the hoses that are connected to them and see where they lead. When you find a hose that is about 3/4" diameter and connects to a pump and most likely a strainer, you are getting close to finding your water intake for the A/C unit. Your A/C unit will not be using 1.5" diameter hoses so you can ignore them for the moment. This is going to be a good safety lesson for you as well. You should know where all your seacocks are located in the event of a broken hose/ flooding emergency. Draw a plan of your boat and mark their locations for future reference.

 

[Don S/V ILLusion]

The strainer/filter are close to the thruhull which is in the vicinity of the keel. As these are aftermarket installations, a generic boat schematic will likely be useless to you.

Assuming you are back in the water, just open the thruhull and strainer to allow it to fill and void any air up to the pump and you should be 'good to go'.

Assuming you are in Missouri, you have plenty of time to figure it out

 

[photo-dude]

I'm sitting in Rockport, Texas, in the boat, in a slip with 8 million percent humidity. Cool weather, north winds and 40% humidity moving in over night so will be perfect "working on the boat" weather.

 

[jcela]

Hi Photo-Dude, I have done the same thing with my 29.5 Hunter, now is a lesson learned, before you take the boat out of the water you must close the seacock that is located next to the strainer or you will drain completely the line and the pump would not work. Now your problem is that the pump used for the marine AC is a pump that would not start unless the line is full of water, having just water in the inlet side would not be enough, you must have the whole line full of water. You cannot have any air in the line. I will tell you how to cheat the system, get a piece of a small hose that will go into the outlet on the side of your boat, where the water normally comes out of the boat, and attached a water hose to it, open the water a little bit and with the seacock open let water into the system. If you watch on the side of the boat where the seacock is you will see bubbles of air coming out as the water keeps pouring in from the outlet few inches above the water line. When the system is full there wont be any more bubbles of air coming out and water will be coming out of the side of the boat, pull the small water hose out of the outlet and now your system is full of water, start your AC and the pump will start pumping water.
Another way would be to close the seacock, remove the hose from the outlet side of the pump, use a smaller piece of hose 3 or 4 feet long, enough for the other end of the hose to be above the outlet on the side of the boat and with a water hose start injecting water into the system to fill it up with water, when water is coming out of side of the boat open the seacock and water will start coming through the pump and into the bilge, rapidly take the smaller piece of hose from the line and quickly insert the line into the pump outlet, tight the hose with two clamps and now your system will be very much full of water with the exception of the little water you lost during your connecting maneuver but you wont have an air bubble in the line and you will be ready to start the AC. This is not the prefer method because the hoses will be very hard to pull from the pump and just as hard to push the hose back into place specially since there is not much room to bend the hoses . If you use the heat of a hair dryer you can softened the hose ahead of time so it would be easy to make up the connections. Maybe someone has an easier method and he/she can share it, otherwise this is how to do it. Hope this helps you to remember to close the seacock next time, I know I will remember. Enjoy your new boat.

 

[photo-dude]

Hi Photo-Dude, I have done the same thing with my 29.5 Hunter, now is a lesson learned, before you take the boat out of the water you must close the seacock that is located next to the strainer or you will drain completely the line and the pump would not work. Now your problem is that the pump used for the marine AC is a pump that would not start unless the line is full of water, having just water in the inlet side would not be enough, you must have the whole line full of water. You cannot have any air in the line. I will tell you how to cheat the system, get a piece of a small hose that will go into the outlet on the side of your boat, where the water normally comes out of the boat, and attached a water hose to it, open the water a little bit and with the seacock open let water into the system. If you watch on the side of the boat where the seacock is you will see bubbles of air coming out as the water keeps pouring in from the outlet few inches above the water line. When the system is full there wont be any more bubbles of air coming out and water will be coming out of the side of the boat, pull the small water hose out of the outlet and now your system is full of water, start your AC and the pump will start pumping water.
Hope this helps you to remember to close the seacock next time, I know I will remember. Enjoy your new boat.

Thanks, jcela. I closed the seacock on the AC but not the one for the motor because I wasn't worried about water coming in and the previous owner, who was with me when it was hauled, said nothing about the seacocks. Could the one left open to the motor have caused this?

 

[kloudie1]

Previous posters are correct .. the pump and air cond was an aftermarket install so there are no wiring or plumbing diagrams for it.. The pump is not self priming so the case has to be filled in order for it to start and work. attached is a picture of my pump (brownish thing on right in the picture; red hose is discharge to air conditioner ) .. yours is most likely installed in a different place.. Find the seacock (valve) supplying the pump (follow the center hose) . Clean out the strainer while you are there.. . You can do what jcela is saying and pressure from the discharge to fill the system.. check very carefully after to be sure you've not blown a hose off, which could sink you.. another way..If your pump is below the waterline, you can pull the discharge hose off and let the pump and strainer fill then put the hose back on and start the pump.

 

[Gunni]

Common problem that justifies an easy remedy - place a small bronze seacock in line on the hose between the strainer and the pump at the elevation of the pump. Crack that seacock open to purge air from the A/C raw water circuit and the pump will prime. Place a short hose on the cock to direct discharge to a cup in the bilge ...and empty.

 

[MitchM]

you can also put a capped T in the line after the pump and before the compressor. if you lose prime, open the AC supply seacock to let water rise into the submersible pump . after you have been on a heel, the water may not rise enough to clear all air from the pump line into the compressor . unscrew the cap of the t and pour water in , the water will displace any air both in the pump and in the line between pump and compressor. depending on the level at which your pump is installed, in a few situations a seacock between filter and pump may not work. to recover from an airlock , fill that tee till it overflows and screw the cap back on. i've had to install this bleed T in both of the 'professionally installed ' air con systems on my boats.

 

[Pat]

The Mermaid I installed had an inline valve that could be opened to aid in priming the ac...If I had been out sailing in say stiff conditions, the AC can loose it's prime...the valve w/thru-hull handle was installed on the water line going from the main thru hull that provides water to the AC pump....Now I know to open the main thru-hull and fill a glass or jar before turning on the ac...-all this with the main thru open....it will quickly fill a glass of water...then shut the in-line valve you have installed and then turn on the AC....and you will have prime....it is quite simple and seems to always work....let me know if you have an issue. Patrick

 

[IH82BL8]

I have the same boat. I can't imagine that the pump is installed above the waterline. So you should have positive pressure to the pump as soon as the seacock is opened. I haven't read all the posts but by now you probably know that the seacock was closed when you started it up.