AC -Raw water pump

[wcconway]

The AC stopped working with an error message of HPF ( high pressure failure). We called our local guy who said the compressor was bad. No way!! The unit wasn't even 3 years old. They removed the unit to bench test it and found it was a $10 capacitor. But the unit continued to shut off with HPF after it was reinstalled.

We got in touch with Hank Bandy at Marvair and he keep telling us it was the raw water pump. We had noticed a slight change in the sound of our factory installed AC raw water pump and it was very hot to the touch. Sure enough we changed it out and no more problems.

What we learned was that the factory-installed RWP was oil cooled and they were not the silver bullet they were made out to be. Our new RWP is a water cooled Dometic.

If you have a Marvair and need help, Hank was great. 229-322-0543 Hbandy@airxcel.com

[wolfe10]

Wally,

Was this a March pump from Dometic? Would appreciate the part number of the upgrade pump in case ours goes out.

Thanks.

Brett

[KenKrawford]

I also had a pump failure last year with my AC system. If you run into the HPF issue, you may also want to flush the raw water AC system by attaching a garden hose to the intake and running a stream of high pressure water through it. If you have enough crud in the line, it can effectively decrease the pump's ability to move water through the system. I had a March LC-3CP-MD pump. I called March about just replacing the impeller unit but they said it is usually the motor that goes bad.

[wcconway]

Replacement part number for raw water pump: Dometic PML 500 L

It has been working great!

[TBOT422]

OK, My raw water pump to the A/C unit has finally quit. Today, while doing other routine issues, I got the HPF error on the panel. I cleared the strainer and nothing changed. I took the pump apart to the impeller as suggested by the manual. There was no debris or 'jellyfish' on the impeller. I thought, hey while this thing is opened up and I can see the impeller I could turn the A/C on for a few seconds and see if the impeller turns. Surprise . . . nothing moved. The impeller was free to turn, so either the pump motor is bad or whatever turns the pump on suddenly failed, or there is a break in the wiring between the A/C unit and the motor.

Does anyone have any idea how to confirm that the motor is dead before I replace it? There's no connector at the motor to check voltage, so I'd have to cut the wires to verify voltage. Does anyone know where the motor wire runs to? Does it go all the way to the A/C unit before any connections?

I put everything back together and hooked up the fresh water flush, so that the raw water pump was not needed to run water through the system, and turned the A/C on and everything worked fine with the water pressure from the fresh water flush.

For those of you who have replaced the motor, did you cut and splice the wires or run the new motor's wiring to wherever it goes?

Thanks for any help/suggestions that you may have.

[KenKrawford]

Gary my motor has a 6 ft cord. http://www.marchpump.com/lc-2cp-md/ My A/C was not a factory install and there was a splice between the pump and the A/C unit. I just had to remove the wire nuts and connect the new pump. I'd bet your pump is bad. Why not just cut the connection a couple of feet from the pump and check voltage. If you have 120VAC, then the pump is bad and you are almost ready to install the new pump. Just make sure your new splices are high in the bilge and away from any potential sources of water.