Carver Owners Forum

Do March Air Conditioning Pumps fail?

My AC pump is wired to run constantly. It feeds two AC units (Salon and Cabin). Cabin unit NFG.

Water output observed at the through hulls is down to about half of prior levels, even earlier this season.

Strainer cleaned. Power cycled.

What gives?

MR

Ya they fail. They run for as long as one of the units calls for water, it will then run to all AC units.You may also have a restriction somewhere that's preventing full flow. Also try pulling the face of the pump off and make sure the impeller spins freely, clean it, the shaft and housing, be careful not to break the shaft, it's plastic. Ensure all the fins of the plastic impeller are there.

If you're handy with a volt meter, check the voltage going to the motor to ensure it's getting proper voltage.

Do you get a lot of water flow if you remove the cap off the strainer?

Another possibility is that it has never primed properly since spring commissioning if you say this started at the beginning of the season.

Thanks Viper,

Yeah, I can check with a DMM - I can't imagine the voltage has gone awry but stranger things have happened.

My relay panel was bypassed by a previous owner and it is hard wired to the breaker panel to operate full time.

I will check if water flow increases if the strainer cap is pulled, but both the strainer and pump are below the waterline so I'm not sure how.

I suppose I could buy a replacement and rebuild this as a spare? Should I bother with a Seaflo or Jabsco version or just stick with the March?

Those pumps usually run, or they don't. Not much in between. I would look for restriction (growth?) on your intake thru hull or restriction through your condenser coils.
Not sure what you Cunuks have to deal with up there, but a friend of mine had a restriction this weekend, a small eel was stuck in the line.

I would go with a Koolair pump. They have a run dry feature and thermal overload which March does not have. Plus they are cheaper. https://koolairpump.com

vineyardgray wrote:Source of the post ....I will check if water flow increases if the strainer cap is pulled, but both the strainer and pump are below the waterline so I'm not sure how......

What I was referring to was a check to see if your intake was partially clogged and restricting flow. What I usually do is shut off the seacock, remove the hose from the strainer end that goes to the seacock, stick a garden hose in there, open the seacock and blast water through it. Usually that blows out things like weeds, bags, etc. that might be trapped on your intake, you could also use a blast of compressed air with an air pig.

I would stick with March or Koolair. The March pump will run for literally hours with no ill effects. Unless you're running the pump without being present, you'll likely notice there's something wrong long before you damage the pump. If everything is mounted correctly below the water line, it shouldn't be running dry but we all know that's not always the case. Once they're primed, you should be good unless you ingest something or the intake gets clogged.

You may want to try and clean your system with a solution product like Barnacle Buster, you may have growth in the lines that's restricting flow. It'll also help with efficiency.

https://boatingindustry.ca/marine-products/5942-how-to-flush-a-c-with-barnacle-buster

The March pump will run for literally hours with no ill effects. Unless you're running the pump without being present, you'll likely notice there's something wrong long before you damage the pump.

He needs to correct the "hard wired running all the time by the previous owner". If he is on the hard and plugs in to charge batteries then his AC pump will have a meltdown.

Ya he should fix that. I think it's switched at the panel though as it will have its own breaker so he's likely turning it on and off manually. I've seen this done before rather than replace the control board due to a bad driver or relay.

Ya I intend to replace *both* AC units this season and will get a proper relay panel to control the pump. I have been limping along on on 16btu unit and there should be a 12btu in the front cabin as well.