AC High Pressure shutdown

One of our AC units has started shutting down with a high pressure error code. It'll run for a while, then shut down. Besides backwashing the unit, which we've already tried, is there anything else we can do before we have to pay someone else to fix it?

We had a similar problem. The digital display on the MarineAir unit read "CLF."
This means compressor load failure. We did what you did plus cleaning all the return air filters and vacuuming the evaporator coils. Could not fix it. Called in a repair company and they had to replace the circuit board. The one last thing I would investigate is to be sure the unit is getting proper voltage. Good luck, Howard

High pressure fault is almost always a water flow issue. Start by cleaning your strainer and making sure your pump is functioning property. Then acid flush all your A/C units.

it doesn't seem to be a flow issue, We cleaned all the lines. The same pump handles another AC unit and its running fine. So it isn't the pump. I'll double check the voltage at the unit.

Have the same issue now with 16K Cruisair unit. Cleaned strainer, blew it out just in case, replaced all cooling lines, acid cleaned coils, flow wonderful but same issue. Bypassed hi pressure switch, same issue. Called A/C guy and he jump wired everything he could, same issue. He says the problem is either in the board or in an internal thermal switch inside the compressor. Taking the unit out now for bench evaluation.

healhustler said:

Have the same issue now with 16K Cruisair unit. Cleaned strainer, blew it out just in case, replaced all cooling lines, acid cleaned coils, flow wonderful but same issue. Bypassed hi pressure switch, same issue. Called A/C guy and he jump wired everything he could, same issue. He says the problem is either in the board or in an internal thermal switch inside the compressor. Taking the unit out now for bench evaluation.

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ugh. good luck! hope we end up with a somewhat faster solution, but it wouldn't be the first thing to get "fixed" multiple times before its right.

Thanks for the info, ours is also cruisair, good to know.

On my salon I get this has always been the waterflow

No Mast said:

it doesn't seem to be a flow issue, We cleaned all the lines. The same pump handles another AC unit and its running fine. So it isn't the pump. I'll double check the voltage at the unit.

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Could it be that all (or most) of the water flow from the pump is being directed to the AC unit that is working fine? I would think that a blockage in the portion of the line supplying the bad AC unit (or in that unit's discharge line) could create that problem.

FWIW, I occasionally had that problem with an ice maker (one that produces 800 pounds of ice per day). I solved the problem by installing a higher capacity pump.

I have always had low water flow out of my front AC I always felt. One shared pump which I upgraded about 5 weeks ago. All the same maintenance approaches as listed except I didn't replace cooling hoses until two weeks ago. Wow. Front discharge now looks like one that you pass on the pier and think "sure wish mine flowed like that". Lots of obstructions in the hoses. Mucho barnacles.
An idea to ponder if you replace your hoses. I used a 5/8" male barbed grey plastic union- connected new hose and old together. Afterwards screwed a couple of #6 x 1/2" ( I believe) screws into the coupler. Sunk these into the hose to streamline things. This allowed me to pull the new hose through bulkheads/ etc. with the old hose.


1983 Present 42 Sundeck
Twin Lehman 135's

Products like Rydlyme, Barnacle Buster, or Triton Marine will get a lot of stuff out of the hoses...


-Chris

Air handler

Fighting same issue. Water flow was OK. Replaced defective (very noisy) compressor unit. Same problem HPF code. Apparently when compressor deteriorated, "junk" clogged air handler. So now this is on order.
We'll see....

If you are acid washing the water circuit make sure you are circulating the acid ,not just pumping it overboard. Take a 5 gallon bucket and installed a thru hull fitting at bottom and just take hose off intake put on bucket ,disc change hoses into bucket and run pump for an hour or so. Then put city water to intake and flush to force shells ,growth on hose ,etc out of system. Acid may loosen stuff or dissolve build up put things can get hung up . Also flush with city pressure from discharge to pump connection ,that way you push out caught stuff inline.

No Mast said:

it doesn't seem to be a flow issue, We cleaned all the lines. The same pump handles another AC unit and its running fine. So it isn't the pump. I'll double check the voltage at the unit.

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By clean the lines what do you mean? Acid flush? The flow can be good but if the tubes are coated with scale you will not get proper heat exchange. Hence the high pressure fault.

I would replace the freon filter/dryer.

A drop of moisture in the system will shut it down.

ok I'll go back and check our lines closer. Maybe I didn't do the acid flush long enough. I'll also pull the hoses from the pump and visually check them.

This is what Barnacle Buster cleaned out of my AC after four seasons of use in mainly brackish water. If you have one pump servicing two units, you might try blocking the flow to the good unit and trying the system with only the problem unit running and getting flow.

FF said:

I would replace the freon filter/dryer.

A drop of moisture in the system will shut it down.

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Yes, best course of action is to just start replacing things willy nilly.

BlueYonder said:

If you have one pump servicing two units, you might try blocking the flow to the good unit and trying the system with only the problem unit running and getting flow.

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Now thats a good thought! Hmm, I honestly didn't think about that. Of course, will do. thanks!

High pressure shutdown is usually high pressure in the condenser, the water cooled loop. Most have a pressure sensor there, which of course could be bad. Usually low water flow or fouled insides of the heat exchanger. When two units share a pump, it easily could be one getting more of the water flow. Hopefully you have a discharge for each so you can visualize flow.

One trick is to check temp of water coming out of the condenser. Also check temp of refrigerant coming out of condenser. If water is cool with good flow and ref is hot, fouled HX. If water and ref are hot, poor flow. If both are cool, then bad p-sensor or goofy expansion valve or clogged filter/dryer.

At some point you may need a tech with a gauge set to read actual pressures.

I finally found this pic of the inside of the front AC hoses I discussed earlier-
Note: these barnacles were attached inside the dark blue hose.


1983 Present 42 Sundeck
Twin Lehman 135's

Clear hose in any boat system can be a disaster.

FF said:

Clear hose in any boat system can be a disaster.

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Bit slow this morning - please explain.

Me too. Fast Fred?


1983 Present 42 Sundeck
Twin Lehman 135's

Clear hose allows light to enter , .

In Fresh water it will grow green stuff ,that you get to drink,

in sea water amazing stuff still grows but it is darker.

It costs more in time and is slower to install but copper tubing , or heavy sea water rated hose is a better long term choice.

Good point Fred- but these run through the bilge so no light to enter. Copper sounds rugged and would flow well until it began to get marine growth. On our boat- and most I suspect- the supply and discharge hoses are too buried to actually remove one end and set up a circular flush.
Man- on the cross section of hose I posted, I had made every attempt I could mechanically to clean the hose. Straightened curves, high pressure water, etc.
I was amazed it had THAT much obstruction !


1983 Present 42 Sundeck
Twin Lehman 135's

Note the barnacles in the picture are alive and well in the solid blue hose. As with a lot ofvthings that can clog an A/C line, they don't care that much about light, as long as they have fresh food being pumped to them they will be happy.

After a few days of running without issue we can update this saying it's been fixed. The problem was in the relay box between the AC pump and the two compressors.

Air handler

sum escape said:

Fighting same issue. Water flow was OK. Replaced defective (very noisy) compressor unit. Same problem HPF code. Apparently when compressor deteriorated, "junk" clogged air handler. So now this is on order.
We'll see....

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New air handler solved the problem as expected. Nice and cool now! Wallet a bunch lighter though....