Air Conditioner help, no water flow!

Tom, it makes since to me. If you have the seacock open and a/c off, water will flow through the system on plane by being forced into it, I put a tee in mine so i can hook garden hose to it while on the trailer. Water flows out before the a/c is even turned on (forced induction) thats why it will operate on plane. My moneys on a bad water pump.:grin:
 
susanandlance said:
Tom, it makes since to me. If you have the seacock open and a/c off, water will flow through the system on plane by being forced into it, I put a tee in mine so i can hook garden hose to it while on the trailer. Water flows out before the a/c is even turned on (forced induction) thats why it will operate on plane. My moneys on a bad water pump.:grin:
Click to expand...

Interesting conversation on a couple of fronts, when running on plane water does not push through my system unless the AC is on, what keeps the water from pushing through if the AC is off? Some sort of shut off up on the compressor unit or the pump? I'm thinking the pump. I always assumed the pump was needed to get the flow all the way through the system to discharge but maybe not? Also is your tee after or before the pump, I assume after which means you are not pushing through the pump when using your hose hook up.
 
Good 2 Go said:
Interesting conversation on a couple of fronts, when running on plane water does not push through my system unless the AC is on, what keeps the water from pushing through if the AC is off? Some sort of shut off up on the compressor unit or the pump? I'm thinking the pump. I always assumed the pump was needed to get the flow all the way through the system to discharge but maybe not? Also is your tee after or before the pump, I assume after which means you are not pushing through the pump when using your hose hook up.
Click to expand...

Hmmm....good questions. There would not be a shut off on the compressor since the raw water does not go thru it. Raw water goes thru the heat exchanger coils. When the AC comes on, the pump also comes on, so putting a tee after the pump would mean that the pump would be running with no water - true? So, the tee would have to be before the pump - yes/no? Since there is nothing between the pump output and the thru hull except water hose and coils, then the pump must stop water from going thru the system when on plane - yes/no?
 
Last edited:
You know, I never thought to look and see if water is coming out of the a/c discharge thru-hull when the a/c is off, but seacock open. I would *assume* it would, based on what happened to me last weekend (a/c running only on plane).

My 'T' garden hose is before the raw water pump. PO installed it so it could be flushed when on the trailer. Water -does- exit the thru-hull with the pressure of a garden hose and a/c (pump) off.

The discussion about using a 'T' for purging the air is to place the T -after- the pump...!

I'm betting the pump too. Anxious to get home tonight and remove the front cover and see what I find.

Tom
 
Good 2 Go said:
Interesting conversation on a couple of fronts, when running on plane water does not push through my system unless the AC is on, what keeps the water from pushing through if the AC is off? Some sort of shut off up on the compressor unit or the pump? I'm thinking the pump. I always assumed the pump was needed to get the flow all the way through the system to discharge but maybe not? Also is your tee after or before the pump, I assume after which means you are not pushing through the pump when using your hose hook up.
Click to expand...
Before the pump, right after the seacock. My boat as the previous one, if you had the seacock open while on plane, water flowed through, even w/a/c turned off . Not as strong as if the pump was running, but still flowing through. It doesn't have to be that strong of a flow to keep the a/c running. The garden hose pushes more than enough pressure through the pump to power the a/c. This, I know to be true!!:smt021
 
Just went through this about two weeks ago. I was getting low flow, enough to run one unit. Tried everything mentioned hear with no change. I finally replaced the pump and the unit has been working fine. Since the unit is below the waterline, with the system off, I removed the pump outlet hose, opened the sea cock, waited for water to come out of the pump outlet and quickly re-attached the hose. I am going to add a valve to accomplish this next off season. I went on line and found my pump for $215. Printed out the info took it to West Marine and as always they matched the price. I think the pump listed for $279 at west.
 
UPDATE: So as Lance suggested, I removed the front of the pump. Took off the inlet hose, already had taken off the discharge hose, and removed four phillips head screws. The first part to come off easily was the plastic cover which had a long thin plastic shaft on it. Next was the impeller itself to which was attached a large circular magnet. It was interesting to take apart as there is no direct shaft connection to the motor. These two pieces are all that is in contact with any water. Now I can see how water pressure will circumvent the pump and get through because the water pressure itself will spin the impeller and push through to the discharge port on this housing.

Anyway, third and final thing to remove was the remainder of the plastic housing. This took some effort as I could only get one hand on it, and I noticed there are two copper tubes running into it. These were just pressed into it and look to be cooling tubes to water cool the motor. Once I pried it enough, these tubes popped out and I got the remainder of the housing off. So behind it is another magnet, this one connected to the motor shaft. The smaller magnet on the impeller fits inside this one (though they are seperated from the plastic housing).

I figured that this inner magnet should spin when the motor is running. This would cause the impeller magnet to spin forcing water through the discharge port. It spun very freely when hand-spun. So I started the a/c and jumped down into the ER. Not moving. So my pump is definately not working! Quickly turned the a/c back off.

The only thing I wanted to check now, but I ran out of time last night, was to check the voltage coming into the pump. There is a electrical box against the ER wall where the wires from the pump convert to the romex-style wires leading up to the panel in the cabin. Tonight I will check the voltage across the hot and ground wires and see if there is power present. I assume there will be, because I (again) assume flipping on the a/c breaker in the cabin powers up both the a/c unit and this pump. I haven't looked at the wiring diagrams, but I did not find any other breakers on the boat pertaining to the a/c.

So by tonight I should have a definitive diagnosis!

Tom
 
Last edited:
Tom, Did you hear the pump running when you went to the ER??? If the shaft isn't sheared maybe you just blew a breaker. If not running when selected, maybe it burned up and overheated???? Let us know when ya find out.
 
Tom, the pump only comes on when the compressor kicks on. So, there must be a relay that has to be closed to activate the pump when the thermostat tells the compressor to come on. So, if your compressor comes on, but, the pump does not, then it would seem that the next step would be to find that relay and see what it is doing. You are not going to have a voltage reading at the point that you mention until the compressor kicks on. I'm just trying to noodle it out here, I don't have a schematic to know for sure. You did say that the AC comes on when you are on plane, so, you should have voltage at that point when you check it. I would have to bet that the pump is done.
 
Last edited:
Jerry is right Tom, the pump will only run when the a/c compressor is engaged.
 
susanandlance said:
Jerry is right Tom, the pump will only run when the a/c compressor is engaged.
Click to expand...

Not necessarily. If wired to spec, yes. I have seen folks bypass this feature (don't know why) and opt to have the pump run 24/7. However the boats that run like that are a less than 1% observation on my part.

I'm thinking new pump is in order. Then rebuild the other and keep it as a bench spare or sell it and recoup some money. Hell, it's not like you don't know the thing inside and out by now. You could probably rebuild it in your sleep!
 
Tom
Take a look at your compressor unit and see if you see a red reset button on it. My unit is a Mermaid and it is right on top where it can easily be seen. Since you never said whether or not you have voltage (110) at the pump I can tell you from experience that this may be the culprit. The reset controls power to the relay that operates the pump in the control box. If the compressor head pressure gets too high while you are winterizing it you could possibly have tripped the reset. I did this and had the same problem this spring. It took me about an hour of troubleshooting but that what I found. If you can't tell if it is tripped just push it down anyway and then turn your A/C on and see if the pump runs. While underway you get enough flow from the scupper picking up watter.
 
Tom,

I know this is an old request for assistance but we had our 370 out of the water for some work for the last 5 weeks. When we returned to the slip the AC was operating but we had no water flow. I closed the seacock, removed the outflow line from the pump, turned on the AC, pushed water into the line after the pump (with a garden hose) to get water flowing out of the AC, opened the seacock and held my finger on the back end of the pump to build pressure. Once I hd pressured coming out of the pump into my finger and water flowing through the AC I quickly reconnected the white line to the pump and the system was operating with good water flow.

Also - I did notice that prior to getting this resolved the pump would shut off after about 30 - 45 seconds after turning on the AC prior to getting the water flow corrected

Hope this is helpful to someone.
 
Last edited:
You must log in or register to reply here.

Forum statistics

Threads
113,182
Messages
1,428,060
Members
61,088
Latest member
SGT LAT
Back
Top