I went to turn on the A/C-heat today . No water pumping. A friend stayed on the boat and I suspect that they turned the knob to start but not run and it cooked the impeller on the pump. The pump was running today just not pumping the water. If this stayed on for hrs. like I suspect would it kill the A/C unit also. It was blowing air today. Hoping it is just the impeller.
A/C pump
- Thread starter Brian
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Capt. Bill1
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Turning the control to start only should not "cook" the pump impeller. First open the strainer and see if it's clogged. Then if it's not clogged, or after you unclog it, make sure there is good water flow into the strainer and on through to the pump and that it is primed.
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Air conditioner pumps sit below the seawater level because they are not self-priming and do not have rubber impellers.
Cruisair and Marineair (and probably all others) will shut down the compressor if they over heat. More modern units with displays will show a "high pressure" failure.
You are most likely plugged with no other damage.
Cruisair and Marineair (and probably all others) will shut down the compressor if they over heat. More modern units with displays will show a "high pressure" failure.
You are most likely plugged with no other damage.
+1.
Something caused it to lose prime. After checking the strainer for blockage, re-prime the system. I use a garden hose with nozzle held against the pee hole. You should see bubbles come up from under the boat. When the bubbles stop, the system is primed. It's always worked for me and fellow boaters. Let us know if it works for you. If it doesn't, you have other problems.
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A question about losing the prime. when the system is full of water and sits for a few weeks, how does the water drain down so that the system is dry and need re-priming. Wouldn't that mean there is a leak some where in the system? I can see losing prime when hauled as the water could drain out. But whether the pump is above or below the water line I would have thought the water stayed in the system.
The first thing I did was check the strainer. It was fine. The instructions says "We rely on liquid being pumped to lubricate the Impeller-Magnet assembly spinning on stationary spindle. If the pump is run dry for longer than 60 seconds the plastic may "freeze" onto the spindle." It is a March LC-3CP-MD pump. Can I unfreeze it?
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March pumps develop internal warpage when run dry too long. This is due to overheating. It's probably toast. I had good luck with oil filled Little Giants.
Capt. Bill1
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My point was leaving the system on fan and never switching it to run will not in and of itself cause the impeller to run dry.
You have water at/to the strainer. Do you have water flow at and through the pump? In other words are you 100% sure the pump is primed?
I've seen March pumps run dry far longer than 60 sec. with no damage to the impeller. But if yours is damaged all you have to do is order a new wetted end for the pump.
Capt. Bill1
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If the system is plumbed correctly it shouldn't be losing prime. The pressure of the water alone should keep water at the pump.
But if the pump is to far above the water line it can lose prime. The system is open at the discharge after all. There are no check valves to keep the water from draining back in either direction.
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Properly installed, all air con pumps should self prime. Besides having the pump below waterline, the key is not too have any low/high point in the line between the seacock, strainer and pump inlet. unfortunately, some installers incl. builders often route hose over sringers creating hard to prime system.
No water flow can not hurt your air con as the high pressure switch will trip protecting the compressor. On some systems you may need to reset the high press. switch on the freon line near the compressor. Systems with electronic controls will show a high pressure error and usually self reset.
on older controls, the start position turn the blower on and I believe the pump. Run turns the compressor on. so on Start, the compressor is not even turned on, no damage can occur.
as to running dry, it's never good even for the pump which is why upgrading to digital controls is nice... If flow is interupted, the compressor shuts down and the control will turn the pump off.
check the strainer and make sure you dont' have something stuck in the thru hull. Open the sea cock with cover open to see if you have enough water coming in. note that if you have a plastic bag stuck in the TH, you may have flow in with the pump off but then under suction, the bag is sucked back tight. I always go for a swim to check it out before deciding to replace the pump.
on the march, you can open the pump end and check the impeller, usually without even removing the motor off the its mount, it's just 5 or 6 bolts on the pump housing comver. it's a hard plastic impeller and i've had TWO fail in the past year. i guess with age (7 or 8 years) the plastic got brittle.
No water flow can not hurt your air con as the high pressure switch will trip protecting the compressor. On some systems you may need to reset the high press. switch on the freon line near the compressor. Systems with electronic controls will show a high pressure error and usually self reset.
on older controls, the start position turn the blower on and I believe the pump. Run turns the compressor on. so on Start, the compressor is not even turned on, no damage can occur.
as to running dry, it's never good even for the pump which is why upgrading to digital controls is nice... If flow is interupted, the compressor shuts down and the control will turn the pump off.
check the strainer and make sure you dont' have something stuck in the thru hull. Open the sea cock with cover open to see if you have enough water coming in. note that if you have a plastic bag stuck in the TH, you may have flow in with the pump off but then under suction, the bag is sucked back tight. I always go for a swim to check it out before deciding to replace the pump.
on the march, you can open the pump end and check the impeller, usually without even removing the motor off the its mount, it's just 5 or 6 bolts on the pump housing comver. it's a hard plastic impeller and i've had TWO fail in the past year. i guess with age (7 or 8 years) the plastic got brittle.
Capt. Bill1
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IMHO an Oberdorfer would be over kill for this application. And I like the plastic/ceramic wetted end with no external shaft seals of the March better than the bronze one with external seals of the Oberdorfer over the long haul.
As to plastic bags getting in and blocking an A/C pump thru hull, putting a perforated cover over the thru hull inlet on the hull pretty much eliminates the need to dive under the boat. In most cases just turning off the pump to eliminate any suction will allow the bag to drop or wash away from the cover. You can also back flush the thru hull with water or compressed air if need be.
As to plastic bags getting in and blocking an A/C pump thru hull, putting a perforated cover over the thru hull inlet on the hull pretty much eliminates the need to dive under the boat. In most cases just turning off the pump to eliminate any suction will allow the bag to drop or wash away from the cover. You can also back flush the thru hull with water or compressed air if need be.
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oberdorfers are great pump but i've seen corrosion and / or cavitation issues on some installs. March are a pretty good choice.
yes, an external strainer is probably the best option but many/most boats comes with slotted scoops. As stuff grows around the slots, bags get caught and only partially release when pump is turned off.
that usually happens to me (my own boat or Charmer) at least once a year. usually on a hot day, when immediate action is needed! i remember once it happened around 6am... with the dreaded HPF flashing on the control by my bed
yes, an external strainer is probably the best option but many/most boats comes with slotted scoops. As stuff grows around the slots, bags get caught and only partially release when pump is turned off.
that usually happens to me (my own boat or Charmer) at least once a year. usually on a hot day, when immediate action is needed! i remember once it happened around 6am... with the dreaded HPF flashing on the control by my bed
It did cross my mind that something could be on the thru hull but I opened the strainer slightly and water was flowing in. pascal you are right when I turn on the start that is when water starts flowing. I turned it to run before I realized water wasn't pumping and I heard the compressor come on. So that is good right?? I turned it off and then restarted it back to start a couple of times hoping I was going to see water flowing. No go and that is what me to think it was the impeller. Also you are right pascal on the back of the motor is a plastic housing with four screws. Behind is the impeller and a ceramic thrust washer. What would it look like...warped?? in pieces?? just stuck for some reason.
Capt. Bill1
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Just open it up and see if it spins freely and doesn't wobble around the shaft. If it's messed up it should be obvious.
JOHNNYRENO
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I think everyone has missed the point which is dont let that friend use the boat or any others, it does not sound like they are there to help you fix it either.
Went the boat today anticpating changing an impeller or maybe the pump itself. Just for the heck of it I turned it on and gave it a light tap with hammer. You guessed it .....it came to life and started pumping. I like these type of fixes. Thanks to everyone who was giving their ideas on the problem.
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Brian
March pump failure mode is intermitent failure to start. Since they are encapsulated you cant take them apart to service them. They seem to have a life of 20 years then start to act up. Suggest you lay in a replacement.
March pump failure mode is intermitent failure to start. Since they are encapsulated you cant take them apart to service them. They seem to have a life of 20 years then start to act up. Suggest you lay in a replacement.