Air conditioner water pump not working

TimFromLI

TimFromLI

.
Jan 7, 2014
443
Beneteau 45F5 51551 Port Jefferson
At the end of last season, I noticed that one of my AC water hoses looked like it needed to be retired. So I replaced the hose over the winter. Last weekend I tried running the AC and the water pump did not work causing the AC to shutdown. I looked at the seacock and realized that I forgot to open it. I opened it up tried it again and the same thing happened. The hose is not collapsed and I still see antifreeze in the strainer from the winterization. I don't hear any kind of motor noise like the motor is trying to get a prime. It was getting late and I didn't have time to test the wiring to see if there is power to the pump but I didn't mess with the electrical connections so that is unlikely to be the issue. It looks like it's a March pump - not sure of the model. Do these pumps have a reset button or can they get overloaded from trying to run them with a closed seacock- certainly they can't be that fragile that they'd fry that easily. Maybe I need to burp the new hose?
 
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C

Capt Robbie

.
Jan 24, 2017
670
Hunter 34 Toms River Nj
some of the little giant pumps are oil cooled sealed units and if run dry without any water resistance they can over heat on a thermal overload protector. The internal thermal overload sometimes takes a long time to completely reset even if the pump feels cool to the touch. Also some pumps run very quiet and don’t appear to be on and could simply be air locked.
 
JamesG161

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,752
Hunter 430 Waveland, MS
If I understand correctly you have 2 AC units.
You may have to start both AC's, set to Cooling.

My dual AC has a "Pump Relay Panel" that allows each of the AC units to start your March Pump independently.

What is your AC units Brand and sizes?
Jim...
 
D

dlochner

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Jan 11, 2014
12,799
Sabre 362 113 Fair Haven, NY
You may have an airlock in the discharge line that is preventing the motor from priming. This sometimes happens with my refrigerator water pump. Disconnect the discharge hose from the pump, turn on the pump to see if you get water flow. As soon as you get water flow shut it down and reconnect the hose. You will get some water in the boat, but not enough to sink it.
 
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M

Monterey385

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May 28, 2015
280
Catalina 385 Atlantic Highlands, NJ
March pumps don’t like to run dry so it might have seized (happened to me quickly). Quick test, use a garden hose with light pressure on the input hose ( disconnect from strainer and attach to hose). If water passes through when AC is engaged the pump is probably fine and just needs to be burped at source. No water passing through, pump is probably seized.
 
kloudie1

kloudie1

.
Nov 6, 2006
10,067
Hunter 34 Mandeville Louisiana
As Dave says, the March pump is not self priming. If you loosen the hose on the suction side of the pump you should have sea water flow. If no flow, the pump may be above the waterline (or the hose has a "hump" that is above the waterline) and needs to be primed before it will pump again. The March is cooled by the water flow so if no flow, it will overheat and trip its own thermal cutoff switch which takes a while to reset. It can be helped to reset by applying a little ice to the coil housing..
 
capta

capta

.
Jun 4, 2009
4,909
Pearson 530 Admiralty Bay, Bequia SVG
I also believe the problem is between the thruhull and the pump. However, if you are using a110 vac pump, they are magnetic drive centrifugal pumps and you can run then quite a while before doing harm to them. You need not worry about the impeller as you do on your engine sea water pump.
 
B

Barnacle Bill

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Jun 9, 2008
1,792
- -- -Bayfield
To trouble shoot the pump (if you can't hear it run), disconnect the 3 wires and splice it into a cord that you can plug into a wall. If it works, the pump is fine. If not, replace. If it works, seek other solutions.
 
TimFromLI

TimFromLI

.
Jan 7, 2014
443
Beneteau 45F5 51551 Port Jefferson
Thanks it's probably an air lock. The March pump is a magnetic drive and is not self priming. I'll try your suggestions and report back. I think I'll try a shop vac on the discharge thru hull first that should prime it. The pump hoses are in awkward place.
 
  • Helpful
Likes: JamesG161
TimFromLI

TimFromLI

.
Jan 7, 2014
443
Beneteau 45F5 51551 Port Jefferson
I put the shop vac on the discharge and sucked the water through the system priming the pump. voila it works. Thanks all. I hope this helps someone else.
 
cymeyer

cymeyer

.
Jul 8, 2005
521
Jeanneau 389 Grosse Pointe Farms, MI
TimFromLI said:
At the end of last season, I noticed that one of my AC water hoses looked like it needed to be retired. So I replaced the hose over the winter. Last weekend I tried running the AC and the water pump did not work causing the AC to shutdown. I looked at the seacock and realized that I forgot to open it. I opened it up tried it again and the same thing happened. The hose is not collapsed and I still see antifreeze in the strainer from the winterization. I don't hear any kind of motor noise like the motor is trying to get a prime. It was getting late and I didn't have time to test the wiring to see if there is power to the pump but I didn't mess with the electrical connections so that is unlikely to be the issue. It looks like it's a March pump - not sure of the model. Do these pumps have a reset button or can they get overloaded from trying to run them with a closed seacock- certainly they can't be that fragile that they'd fry that easily. Maybe I need to burp the new hose?
Click to expand
Try again this weekend when it is 80 degrees. Maybe it was not hot enough outside to run the AC?
 
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