Air Conditioner help, no water flow!

[Gunn]

Tried to run the a/c for the first time this year. When I flip on the breaker, the system comes on, but I am not getting any water flow out the overboard discharge thru-hull fitting.

The previous owner had put a 'T' in the line before the strainer to hook up a garden hose for flushing. If I connect my hose to that, I get water flow out and the a/c blows cool air. I thought this might help prime the pump, but as soon as I shut off the garden hose, no flow (yes, the seacock is in the right position!).

So on our day out today, I started the a/c while on plane, thinking the pressure would help prime the pump. Sure enough, we had water flow and the a/c was cooling. However, when I came off of plane and checked, the water flow had stopped. Help! :huh:

Is my pump bad, and so only forcing water through the system makes it work? That's where I'm at right now, but wanted to check with others for possibly other easy solutions to try.

Thanks,

Tom

 

[JC3]

Your thru hull hole on the hull (what a play on words) may be blocked. Good luck, JC

 

[Great lakes pirate]

Try rocking your boat side to side while tied up in your slip with the AC on. I suspect you have air trapped in water supply line.

 

[perkinaustin]

Easy fix. Get down in the engine compartment, and locate the a/c water lines (there should be a white plastic box they go in to). Disconnect the line that comes in from the back of the boat, and get a water hose from your slip and take it down there with you. Right after the white plastic box with the pump in it you'll find the hose that heads in to the a/c unit, and ultimately out to the lake from your boat. Disconnect that hose from the pump, and take your hand and wrap it as tight as you can around both of them end to end so you're forcing water through the system for about 3 or 4 minutes until you see it moving out the side of the boat again. Once you're getting pretty good flow out the side of the boat and the a/c unit stays on you can stop, turn of the a/c, re-connect that hose, and you should be off to the races. If that doesn't solve the problem you might have a bad pump.

Boats in fresh water get algae build-up inside of the lines, which kills the water pressure flowing through there. when you bypass the pump and force water through the lines it breaks the gunk up and washes it out of the lines. The pump can only push so hard, and when their being met with a certain amount of resistance you lose water flowing through. Once you do this it should stay on fine. Good luck.

 

[tbirdvet]

Mine did the same thing this year but the hose system worked for me. Good luck.

 

[Alex F]

Tried to run the a/c for the first time this year. When I flip on the breaker, the system comes on, but I am not getting any water flow out the overboard discharge thru-hull fitting.

The previous owner had put a 'T' in the line before the strainer to hook up a garden hose for flushing. If I connect my hose to that, I get water flow out and the a/c blows cool air. I thought this might help prime the pump, but as soon as I shut off the garden hose, no flow (yes, the seacock is in the right position!).

So on our day out today, I started the a/c while on plane, thinking the pressure would help prime the pump. Sure enough, we had water flow and the a/c was cooling. However, when I came off of plane and checked, the water flow had stopped. Help! :huh:

Is my pump bad, and so only forcing water through the system makes it work? That's where I'm at right now, but wanted to check with others for possibly other easy solutions to try.

Thanks,

Tom

Tom,

Based on what you've tried so far looks like there's no air buble. So, you have to check for blockage in the scoop strainer and make sure that the seastrainer is clean as well. It's possible that you have some growth in the scoop strainer preventing enough water to enter the system when you're not on plane.

 

[susanandlance]

Tom, I had the same problem w/my last searay, it was a broken impeller shaft, the factory pumps use a ceramic shaft and impeller and they do sometimes shear into, like mine did. That would explain it working well w/forced water pressure.

 

[Gunn]

Thanks for all the help and hints. Unfortunately, nothing has worked. I messed with it again last night to no avail. I tried forcing water in the outlet with a hose (tip found searching the forum); didn't work. Tried rocking the boat. No luck. The strainer is perfectly clean, and when I open the seacock with strainer lid off, water pours in at a pretty good rate. I'd think that pressure alone would be enough to prime the pump.

I'm thinking the pump has got to be dead, unless there is a seperate breaker somewhere I'm overlooking? But it worked fine at the end of last season...! I winterized it by blowing compressed air through the lines, and haven't had any other winterization issues withe fresh water system, etc.

I need to run my generator to run the a/c. No shore power at my home dock. So I can't hear if the pump is actually working.

 

[Gunn]

Does anyone know the water pump manufacturer, model #, etc. that I can use to look up a replacement pump that will drop right in?

 

[susanandlance]

Go to e-bay and they are there, you just need to know the gph flow, they start at 270.00 bucks for the replacement one, but when I replaced mine I got the one at west marine, works just fine for 199.00 part # 280050. Lance

 

[susanandlance]

The one you need for the 280 factory style is part# 493965 209.00 at west marine.:thumbsup:

 

[Gunn]

Thanks! But wow, that's way more than I thought. I think I need to do some more troubleshooting first. I've been reading up on these centrifugal type pumps...

An airlock issue seems to be abundant on every boating forum around. I liked the one solution where someone removed the hose from the discharge port of the a/c sea water pump to remove all air. Some have even added a T connection here and placed a ball valve to purge the line of air. I'm going to try removing this line while opening the seacock tonight and see what happens.

The pump on a 280 is difficult to get to though!

Tom

 

[Alex F]

... I winterized it by blowing compressed air through the lines, and haven't had any other winterization issues withe fresh water system, etc...

Hmmm, I wander if this might have any contribution to the issue...maybe not? I always use antefreeze.

If the you have good water flow passed the seastrainer then the next component in question is the pump itself. Running the unit by generator supplying the AC power doesn't solve anything. If the shore power is available and you have 110v going to the pump, by running the genny all you do is supply the same 110v just via different source, which means nothing for the pump. The pump either works or it doesn't having the 110v power.

 

[Gunn]

Alex,

My comment about the generator was only to mentions that that is the only way I have to test the unit. And so I can't hear if the sea water pump to the a/c is running since the gen. is so noisy. I have no shore power at my home dock, at the moment.

I used my air compressor and a connector to blow air through the system until I had no water, only air, exiting the discharge thru-hull. I didn't think I would be able to get antifreeze through the system since the pump needs positive pressure, and it's not going to get that by sticking a hose in a bucket of antifreeze? But I guess that's another topic for another day!

Thanks,

Tom

 

[susanandlance]

Thanks! But wow, that's way more than I thought. I think I need to do some more troubleshooting first. I've been reading up on these centrifugal type pumps...

An airlock issue seems to be abundant on every boating forum around. I liked the one solution where someone removed the hose from the discharge port of the a/c sea water pump to remove all air. Some have even added a T connection here and placed a ball valve to purge the line of air. I'm going to try removing this line while opening the seacock tonight and see what happens.

The pump on a 280 is difficult to get to though! Mines not that difficult to get to, right beside the batts. on port side. You can check the pump, close the seacock valve, then disassemble the white portion of the pump to see if the shaft sheared. Then you'll know for sure if ya need one. Disconnect the two water hoses, then take the white plastic portion apart, thats where the impeller and shaft are located.:thumbsup:

 

[gerryb]

You need to be able to run the pump without the genset to understand and diagnose this. Don't take the pump out unless you know it is not working. Get a long extension cord and an adapter to the boat for electrical hook-up. then see if you hear the great 'whirring' sound when you turn the tstat down. If no sound, check for electricity to the pump using an ac line tester (you don't need a multimeter but that would also work) . If you hear pump turn on, it is getting juice and it is either in need of repair or you have an air lock. The steps you have already performed should take care of the airlock. (Waterhose into the outlet worked for me in the past) I would then take the inlet and outlet ports off the pump and check there is no blockage or problem with the inlet portion of the pump. Hit both ends with a water hose. Reconnect, prime it again, and see what happens. If still nothing, then I would pull the pump out at that point.

 

[Gunn]

Thanks again for the help. So this evening I went down and removed the discharge hose on the a/c sea water pump. I then opened the seacock. Water poured in steadily. Not gushing, but not trickling either. Just a slow steady pour. So then I started the generator, started the a/c and checked again. Same flow rate. No change. Has to be something with the pump.

I have a home 30A generator that I could wheel down to the pier and power the boat from 25' feet waway, so that I could hear the pump running. But I think next I will try what Lance said and remove the front portion of the pump and see what I can see.

Arrgggggh :smt001,

Tom

PS> I love WestMarine's website for the pump part #. It currently says "Hot Seller. Temporarily out-of-stock. Order Now" ...

 

[Good 2 Go]

Sounds like you have been around the block on this one but I prime mine each spring by running the AC while on plane, after that it always holds the prime. I have the 'T' valve described in this thread but have never had any luck getting a prime using it, pump runs but will not push the water up to the unit under the V-berth, it's a long run. Have you tried a second run at plane to get it pumping and then off plane and see if it continues to pump? If yes while off plane the pump is working, if you shut it down and it will not pump then you have a priming issue or an air lock.

I don't think running on plane would push enough water through to adequately supply water to the unit without the pump working, as stated the pump either works or it doesn't for the most part. Air lock somewhere seems the most likely, the pump on my 340 will not overcome air anywhere in the system, it needs the pressure of running on plane to help get a good prime then it's good for the season. If you did a thorough job of blowing out all the water there could still be air somewhere in the coils the pump cannot overcome.

I winterize using antifreeze, 5 gallon bucket with fitting to a hose held above the sea strainer, I have a spare lid to the strainer drilled and tapped with hose barb to connect to the hose from the antifreeze bucket. You'll find lots of post out here on how to do that, once you are rigged for it only takes 5 minutes to do.

 

[susanandlance]

:thumbsup:Tom, E-Bay has the same part # for the factory style pump your looking at, and no back order. You will know right away if it's the pump when you take the housing off of it Tom. Let us know what ya find. Domedic is the manufacture of the factory pump. Lance

 

[Gunn]

I don't think running on plane would push enough water through to adequately supply water to the unit without the pump working, as stated the pump either works or it doesn't for the most part. Air lock somewhere seems the most likely, the pump on my 340 will not overcome air anywhere in the system, it needs the pressure of running on plane to help get a good prime then it's good for the season. If you did a thorough job of blowing out all the water there could still be air somewhere in the coils the pump cannot overcome.

I winterize using antifreeze, 5 gallon bucket with fitting to a hose held above the sea strainer, I have a spare lid to the strainer drilled and tapped with hose barb to connect to the hose from the antifreeze bucket. You'll find lots of post out here on how to do that, once you are rigged for it only takes 5 minutes to do.

I have not tried a second run on plane. But during the first run, water was pumping through the system while on plane and the cabin a/c was working well. This was on a 45 minute or so ride. But once we came off plane, I looked overboard and there was no flow at that point. The a/c had shut down with an error on the LCD. I would have thought that would have been enough to prime the system. Your comment about running on plane not being enough to push water through is interesting... Though my report last night of the test by removing the discharge hose and running the a/c seemed to indicate the pump is doing nothing.

Now that I know more about these centrifigal pumps, I understand how they work, and how to winterize...by keeping the bucket of antifreeze at a higher level than the pump...!

:thumbsup:Tom, E-Bay has the same part # for the factory style pump your looking at, and no back order. You will know right away if it's the pump when you take the housing off of it Tom. Let us know what ya find. Domedic is the manufacture of the factory pump. Lance

I was this EBay item; and Defender.com has it also. I few bucks more than WM, but I like Defender and they'd have it to me before the weekend. Though the weather is nice here for a change and the a/c thankfully won't be needed. So I have some time.

The pump number you gave me does indeed look like the one I have. It's a Dometic March pump. From what I've been reading, they get very good reviews.