Need Advice: CruisAir Water Pump Troubleshooting - No Water Coming Out

[solecollector]

I need some help troubleshooting what I think is a water pump issue.

My boat has four CruisAirs on it - on the starboard side there is one air conditioner and one pump and on the port side there are three air conditioners. I noticed just a trickle coming from the port side and Niagara Falls on the starboard.

Pump: Dometic Model PMA1000


What I've done so far is:

1. Disconnected the incoming water hose coming off the seacock. Water flowed through the seacock no problem. Water also flowed the other way from the pump to the seacock - the pump wasn't on....

[solecollector]

Damn - not all of my post went through. Here is the rest:

2. I turend on the water pump and disconnected the hose - the water was sucked into the hose. I tried to put the hose back on quickly but some air got in the hose and the pump started making a different noise. I looked outside and no water at all was coming out.

3. I took apart the wet end of the pump and the impeller looked okay - wasn't sure exactly how it should look as I've never seen one like this.

4. I turned on each air conditioner separately - none of them had water coming through.
So that is where I am at! Hosed one way or another...


Thanks for any isight! _steve

[poiu]

Originally Posted by solecollector

Damn - not all of my post went through. Here is the rest:

2. I turend on the water pump and disconnected the hose - the water was sucked into the hose. I tried to put the hose back on quickly but some air got in the hose and the pump started making a different noise. I looked outside and no water at all was coming out.

3. I took apart the wet end of the pump and the impeller looked okay - wasn't sure exactly how it should look as I've never seen one like this.

4. I turned on each air conditioner separately - none of them had water coming through.
So that is where I am at! Hosed one way or another...


Thanks for any isight! _steve

You might have air in your pump. These pumps need bleeding before they work. There might be a screw or tap to turn to vent the air. If not, then try to loosen the outlet hose to get it to fill.

Once filled you need to find why the units have little flow. Sounds like a blockage downstream or less likely, a damaged impellor. You can measure the flow at the pump if the impellor is suspect after removing its outlet hose. if it is fine then look downstream. Barnacles can do this. They get in as babies and grow big.

You can disconnect the pump also and run it dry to see it spins nicely. Inspect the blades looking down the in/ outlets, but I don't think it is this as you have Niagara Falls.

[sailnow2011]

unequal pressure. One AC unit is easier to flow thru then the other.
Clean the raw water passage on each of the AC units. and if your pump is below the waterline as it should be, just take the hose off, with it shut off, and let the water flow back from the AC units into the bilge. With seacock closed.

[Abgreenbank]

If you need spares or a new pump dometic just put their name on a march ac 5c magnetic drive pump and charge lots more than march. These pumps are not self priming so need to be below waterline and a nice uphill flow from the seacock to pump. Good news is that they are very reliable but don't like to run dry for too long, and march spares easily sourced on ebay etc. not sure that a single pump is man enough for 4 AC units, certainly does 2 x 16k btu units fine.

Regards

Ab


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[redsky49]

Start with bleeding the pump and re-establishing confirmed flow.

As I understand your post, a single seawater pump serves (4) AC units. Do all (4) units operate independently, or does a single thermostat energize the entire system? Is pump sized correctly for all units to be operating simultaneously?

I will assume that any single AC unit, ....

Too many assumptions! Please describe seawater piping layout and control system. Unable to diagnose based on available info.

In a commercial (non boat) installation there would be provision to "balance" the system, i.e., balancing valves at each connected device to adjust individual flow per requirements. Do you have such valves on your system?

[solecollector]

Hello all - ~ ! And thanks for the advice. I'll have some pictures posted tomorrow when I go back over to the boat. In the meantime - here is a little more info.


There are three air conditioners running off this one pump. Two 7k BTU and one 10k BTU. They are all independent and get their water flow directly from the manifold off the pump.

When can run the air conditioners in any combination and no water is coming out. I've turned each of them on separately as well as all together and no water.

If one is clogged up (which I just had the lines cleaned - looked like some nasty ass brown oatmeal...) would none of them work? Common sense would say if one is down the rest would work... but I'm a newbie in this area so common sense is thrown out the window._steve

[Clamdigger62]

I was a Cruisair dealer in my early years. If the pump is running and no water flow, pull the discharge hose off the pump while the pump is off and let the water flow thru the pump. If no flow you have a clog down stream, if you have a good flow, put the hose back on and turn on the pump. If the pump is running and still no flow you have a bad impeller, rarely the case. Air bound pump 80% of the time.

Now if the pump is not running and it serves more then one A/C unit you will have a pump relay box. Check to see if the relay box is getting power, easy way to check is there is a light on the motherboard or use a volt meter. The inside of the box is well labeled. Please be ever so careful you are working with live AC current, if unsure get someone who knows. If you have voltage to the relay box and no pump, look and you will see a small rectangular board with a diode in the center held in with 2 screws. You will have one for each A/C unit it services, they are called triggers and have a tendency to burn out. I use to keep a bunch on my service truck.

If you have a single unit check to see if you have power to the pump, easy way is to read out put voltage to the pump on the main board which is well labeled. If you have voltage and no pump you have a bad pump. A bad electrical end to the pump will normally trip the breaker.

A pump that serves multiple units will normally have its own breaker on the main distribution panel

[mausgras]

Ditto. ... bleed your lines. I get an air blockage almost every time I go out. Also once found a barnacle growing just inside the thru hull.

[DeepFrz]

It is also possible that there was still some junk left in the cooling water circuit. If the above advice doesn't work try back flushing your cooling lines. Isn't there usually a strainer after the through hull?

[Scrimshaw4]

Just some thoughts if your TH is clear. There should be a RW filter (basket type) between the TH and the pump. Check that it's clean and correctly closed or air will get in the line. Disconnect the output side of the pump, not running and TH open. If water comes out then the impellor is worn and needs to be changed. Using your dinghy air pump, pump air into the pump output hose. If you get back pressure then blockage is in the system, probably where the line splits to service the units. Check your bilge to see if water is there. This would mean a leak in the lines. ...

[ranger58sb]

Originally Posted by solecollector

I noticed just a trickle coming from the port side and Niagara Falls on the starboard.

Symptomatic of a clog in the one line that doesn't properly discharge. Clean by back-flushing, or better, remove that line from the manifold and flush in the direction water usually flows.

Originally Posted by solecollector

There are three air conditioners running off this one pump. Two 7k BTU and one 10k BTU. They are all independent and get their water flow directly from the manifold off the pump.

When can run the air conditioners in any combination and no water is coming out. I've turned each of them on separately as well as all together and no water.

If one is clogged up (which I just had the lines cleaned - looked like some nasty ass brown oatmeal...) would none of them work? Common sense would say if one is down the rest would work... but I'm a newbie in this area so common sense is thrown out the window._steve

If the pump runs.... You've likely just lost prime during your troubleshooting. These pumps are usually not self-priming, but all you usually have to do is bleed the air out.

If loss of discharge on that one line happened after you had all your lines cleaned, you may have launched a jellyfish through there (or some such) causing the new blockage.

Or...

A discharge line can pop off the discharge port at the AC unit, or at the discharge thru-hull. In that case, you'd not be seeing any fault codes on your thermostat... and you'd be pumping water into the boat somewhere. IOW, if you're not seeing fault codes, start checking line connections at the unit and at the thru-hull.

-Chris

[solecollector]

Thanks all for the most excellent advice!

Here is what I did today as instructed...

1. Took off all of the hoses on the manifold - one by one. Water flowed from the pump through all of them. I then turned on the pump - and water came out like crazy... after washing it all down with fresh water I proceed with the next step...

2. With the pump off - I disconnected all of the hoses on the manifold again and this time was looking for water coming back out the hoses. The two on the right water came pouring out but the one of the left - no water came out at all.

I assume there is a problem with that line? And would that affect the rest of them??

[ranger58sb]

Originally Posted by solecollector

Thanks all for the most excellent advice!

Here is what I did today as instructed...

1. Took off all of the hoses on the manifold - one by one. Water flowed from the pump through all of them. I then turned on the pump - and water came out like crazy... after washing it all down with fresh water I proceed with the next step...

2. With the pump off - I disconnected all of the hoses on the manifold again and this time was looking for water coming back out the hoses. The two on the right water came pouring out but the one of the left - no water came out at all.

I assume there is a problem with that line? And would that affect the rest of them??

To be sure I've interpreted what you said correctly....

The pump works well, and sends water through each of the three outputs on the manifold, yes?

You found water still remaining in two of the three hoses leading from the manifold, and that drained back into the boat as you disconnected them from the manifold, yes?

No water drained from the third line that exits the manifold, right?

If all true, I would at least expect that third line to be the first suspect. ( And if it's just clogged, dockside water pressure may be enough to clear it.)

When your system is working properly, do you usually have three separate thru-hull discharge outlets? Do you know which is which? If you turn the systems on, do you see running water from all three outlets? (We have two ACs, and one will run -- as long as the pump is supplying water -- even if the other is showing a fault code.)

Can you tell if that one line is actually connected properly to its AC condenser unit? Is there are discharge hose properly connected on that condenser unit? Is that discharge hose properly connected to the thru-hull discharge outlet? (Water flow should be through that suspect hose into the condenser unit, through the condenser unit, out another hose to the thru-hull discharge outlet.)



FWIW, I have separate breakers for each AC AND another separate breaker for the water pump. When the pump breaker is on, water only flows when demanded by one of the AC units... and in that case, water flows through both AC systems. If I turn on one or the other of the AC breakers without having switched the pump on, the AC's will start but pretty quickly shot down with a fault code showing. I can't tell from your description whether you have similar breakers or not, so I just throw that out there in case...

-Chris

[memiller279]

Also, while you're at it - do a cleaning of the water circuit through the units themselves. Close the discharge thru hull and connect the intake/discharge to hoses leading to a bucket that has Barnacle Buster (diluted) in it. Run a pump on the intake hose of the AC unit and let it circulate for an hour or more (depending on how long you want to sit there and watch it. It's amazing how much stuff comes out of those units - especially if they've been sitting.

After you're done, run some fresh water through it and you should have better flow than before (if it was fouled by critter growth).