Hunter 49 A/C pump replacement (original pump shorting)

senang · Jan 18, 2020

My Hunter38 is wired for 2 AC units but only 1 is installed. The 220V pump is a Little Giant, model U21B. It uses a magnetic drive of the turbine wheel, so never water in the engine part. Just know that you have 2 small oiling holes above the bearings. I oil these 2/year. One hole is inside the wiring box! On their website you should be able to contact them for your 3 AC requirement.

Edit: Sorry type is 2-MD-SC is on another label.

Terry Cox · Jan 18, 2020

Our 1991 boat has two working units; 16k BTU main/forward cabin and 9K BTU aft cabin. Both use an original Little giant sea water pump that I'm pretty sure is 110 VAC. As snang said, the magnetic sea water Delrin impeller is isolated from the motor and rides on Delrin shims. Unaware of any lubricate ports on our motor. Unsure how any electrical leakage would find its way to the sea water plumbing. Perhaps your marina might have some stray leakage from nearby boats, which is a possibility.

JamesG161 · Jan 19, 2020

TT Tide Together said:
I think the original pump is a March pump.

Mine is a March type also.

But...

I think you need to do some trouble shooting to find the "tingle" source.

Why?
It could be coming from another boat!

Turn off all 3 AC units and the water pump on your AC breaker panel.

Still a tingle on suction hose?
Jim...

SEMPERAVANTI41 · Jan 19, 2020

I agree with JamesG161 but I would also remove the suction hose from the strainer to completely isolate it. If this is a stray current issue, I would also check to see if the same "tingle" exists on the suction hose for the engine. Perhaps you could also check any electrical leak with an electrical meter, as I don't see how the rubber of the hose would not act as an electrical insulator.
FYI, I don't think the same hose on my Hunter 50 is wire reinforced.

JamesG161 · Jan 20, 2020

TT Tide Together said:
pump relay breaker

If the water pump is working and water flow is good overboard, then I have a good guess where the problem is.

The pump relay circuit board.

https://tampabaymarineair.com/online-store?olsPage=products/pump-relay-panels-2-prp-2-6prp

above link to show what I am referring to.

I had mine recently bite the dust.

That Circuit board starts your water pump when at least one of your 3 AC units starts up.
Jim...

PS: The March pump motor does not have electrical contact to the water , since it is a magnetic drive.

JamesG161 · Jan 20, 2020

You can check your Water Pump housing to ground also for stray current and here is the replacement.
https://tampabaymarineair.com/online-store?olsPage=products/march-lc-3cp-md-510-gph-115v&page=3

Jim..

SG · Jan 20, 2020

Trying to find the brand and model, size of raw water pump used (original) for serving all three A/C units (18k, two 10k BTU). On my 2009 model, the pump is working properly, but there’s some sort of electrical short as when I touch the pick up hose I can feel electrical current coming through the (wire-reinforced) hose. Is this an internal issue in the pump, or would there be a short or ground issue outside of the pump?
I know the pump is 240v type. What pump replacement options (brands) are best suited for this set up?

The March pump, as noted by Jim is a non-displacement (non-self priming pump) which has a magnetic drive. The RED FLAG, that I don't like is the electrical short issue which appears from your comments to clearly be an AC thing -- "tingle".

The pick-up hose implies that it's from the seacock to the pump? What type of strainer/filter do you have on the intake? What type of seacock? (I'm asking about continuity for the flow of AC power.) Is your thru-hull grounded? (it won't be if it's plastic thru-hull)

Can you measure any electrical charge with the AC pump OFF -- or is it only related to what's happening when you turn that pump on?

AC leakage is a very troublesome issue -- aside from electrolysis problems, it kills people -- especially on boats. If you are GROUNDED and the best path of current, you're clearly in harms way.

It's possible that the pump has an issue with it's case -- but, I'd suggest some trouble shooting to determine where the source is.

senang · Jan 20, 2020

Terry Cox said:
............ Unaware of any lubricate ports on our motor.............

I am an hour’s drive from the boat, but found this old picture. I marked the inlet for the lubricating channel. The other one is hidden in the bottom of the electrical connection box, real difficult to find.

JamesG161 · Jan 20, 2020

This is a complex issue to trace a Leaking voltage from the Air-conditioning System.

Example: AC#1 has a compressor motor that leaks voltage slightly.[ not enough to trip the breaker]

When AC#1 Starts it tells the March water pump to start via the Pump Relay Panel.
Then the sea water conducts that leaking voltage from boat ground to the Water input thru hull and strainer.

So..
It is a step by step [breaker by breaker] approach to find the source of the VAC current leak.

Jim...

PS: Please note I sent the Dometic Replacement parts in my post 7 and 8. Not the AC compressors.

Terry Cox · Jan 20, 2020

senang said:
I marked the inlet for the lubricating channel.

Plan to take a closer look at ours the next time to the boat in a couple of weeks. Will post what I find here.

Several years ago was running the system during a winter night cold spell and heard the Little Giant beginning to falter. This was before we had a furnace. Next day I took apart the impeller assembly and found that the Delrin bearing closest to the motor had become unseated from its race. I suspected the PO had taken it apart once before to clean it and had not put it back together properly. Reassembled the pump and it has run flawlessly ever since. Thought at the time the motor was reaching the end of its life, but not yet.

The system does not get that much use. Never during the summer, but a few times during the winter when spending a night or two while connected to shore power. Always amazes me at how much heat it can extract from 45 degree water.

JamesG161 · Jan 20, 2020

TT Tide Together said:
The thru hull seacock is metal (bronze) and grounded with all the other seacocks.

I am surprised if they are truly grounded by a separate wire to each seacock, then to the boat ground.

Turning off the Pump Relay, turns off the power to that printed circuit board [PCB] too.

I am looking at my old PCB for the Compressor wiring.
I think the green wire for each AC unit has a common ground point, but can't remember.

The Pump Relay Box should be close to the Power box on your largest unit or near the March pump.
If you see Black, White and Green wires coming from the AC compressors then they may be conducting too...

Until...
You turn off the Pump Relay Panel breaker.

The PCB uses a solid state relay [Triac] and it detects VAC and holds to activate the pump.

Each Air-conditioning compressor has its own Triac. Power off may not disconnect the Green wire.

Complex system = Complex troubleshooting
Jim...

PS: @SG your link did not link for me

artboas · Jan 20, 2020

TT Tide Together said:
Trying to find the brand and model, size of raw water pump used (original) for serving all three A/C units (18k, two 10k BTU). On my 2009 model, the pump is working properly, but there’s some sort of electrical short as when I touch the pick up hose I can feel electrical current coming through the (wire-reinforced) hose. Is this an internal issue in the pump, or would there be a short or ground issue outside of the pump?
I know the pump is 240v type. What pump replacement options (brands) are best suited for this set up?
I think the original pump is a March pump.
Thank you for any advice!

My 49 has a Cal Marine pump. It is 220v, and runs all 3 airco units.
I suspect the leakage is in your pump, or one of the airco motors.
This isn’t easy to troubleshoot. Means separating everything at the relay box, and testing circuits individually. Only conclusive way to figure this out.
I suggest you get a pro electrician who has hipot test equipment which tests for insulation breakdown at 500 or 1000vdc.
You can’t do this with a regular DVM
These are called Megohm meters, dielectric breakdown testers, hipot units, etc.

senang · Jan 21, 2020

senang said:
I am an hour’s drive from the boat, but found this old picture. I marked the inlet for the lubricating channel. The other one is hidden in the bottom of the electrical connection box, real difficult to find.

Updated picture, the oiling point is indicated here. Precedent photo was showing it in the split for the ventilator.

Terry Cox · Jan 22, 2020

JamesG161 said:
Complex system = Complex troubleshooting

Agree, Jim. The sea water pump seems pretty simple and have taken it apart before, as mentioned above. Heat pumps, on the other hand, are above my pay grade. Both 1991 original units remain operational. A couple of years ago the aft unit stopped producing heated air and I suspected it was low on gas (R-22). Hired a local AC guy to check it out, and sure enough, it took a charge. He tested both systems while there and gave them a clean bill of health.

Chrit · Mar 29, 2020

artboas said:
My 49 has a Cal Marine pump. It is 220v, and runs all 3 airco units.
I suspect the leakage is in your pump, or one of the airco motors.
This isn’t easy to troubleshoot. Means separating everything at the relay box, and testing circuits individually. Only conclusive way to figure this out.
I suggest you get a pro electrician who has hipot test equipment which tests for insulation breakdown at 500 or 1000vdc.
You can’t do this with a regular DVM
These are called Megohm meters, dielectric breakdown testers, hipot units, etc.

I think I also need a replacement pump for my 2007 Hunter 49 -- it is making odd noises and running VERY hot. I can see that it was a Cal Marine, 220v, but all other printing is rubbed off. Do you know what size (GPH) is your pump? Thanks!

artboas · Mar 30, 2020

Chrit said:
I think I also need a replacement pump for my 2007 Hunter 49 -- it is making odd noises and running VERY hot. I can see that it was a Cal Marine, 220v, but all other printing is rubbed off. Do you know what size (GPH) is your pump? Thanks!

Think it’s 1200 gph
Defender sells these for about $230.
If you have the Cal, then suggest you stay with it. Redoing the hoses and the mounting is a pain.

Hunter 49 A/C pump replacement (original pump shorting)

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