AC kicking off on hi ps with good water flow

[motoryacht lover]

Have a cruisair unit that will cool fine for 5-6 hours then will cut off flashing hi ps. Will reset unit and it will run fine for maybe hours or 20 minutes and shut off again. AC repair guy replaced triac and hi pressure switch. Still same issue. Water flow is fine other 2 units operating fine off same water pump. What is the next step? Thanks for your time.

 

[carolinacoast]

If the unit failing is highest in the boat, I would check the water pump and make sure it is performing to rated spec. We had something similar and the raw water pump needed a rebuild. There was too much resistance in the motor, and flow was reduced. Only the salon unit ever cut off.

 

[motoryacht lover]

The unit is one of the lowest in the boat, but you make a good point that I had not thought of. Also new pump just installed.

 

[saltshaker]

Turn off all other units and run just the one that is failing. Check water flow. If it's not pumping water you have a bad or disconnected start capacitor. If it still behaves the same, you may need to clean the unit. If the ACs share a common discharge, you won't know if the failing unit is actually getting a good supply of cooling water unless you can block off the other units.

 

[captainwjm]

Also, make sure the blower is running on high. That solved my problem.

 

[Tim Powell]

Have a cruisair unit that will cool fine for 5-6 hours then will cut off flashing hi ps. Will reset unit and it will run fine for maybe hours or 20 minutes and shut off again. AC repair guy replaced triac and hi pressure switch. Still same issue. Water flow is fine other 2 units operating fine off same water pump. What is the next step? Thanks for your time.

It is hot as hello here in Hatteras NC. My salon ac was doing the exact same as yours. WATER FLOW WAS THE PROBLEM. New as units installed last year. The AC guy was stumped. Ran cleaner through the AC coils all ok now. SEEMS COIL WAS COATED WITH LIGHT COAT OF MUD SAND COMBO. Not much water in slip at hard north wind strainer was proof.

 

[Finalee]

I experienced something very similar that ended up being a failing H/S switch. Cost was $75 and easy to change.

 

[Tim Powell]

I experienced something very similar that ended up being a failing H/S switch. Cost was $75 and easy to change.

Hi Fred explain H/S switch i am AC stupid along with other topics. Shut up Freebird!!!

Tim

 

[Finalee]

Well I was born in Havelock and it stands for high pressure switch. Probably only made sense to me. I see he already did that . It is likely a real high pressure shutdown. My next move would be to get some gauges on it and see how close to the limit that unit is.

 

[Pascal]

I would start with descaling if it hasn't been done in a while and check pressures before starting throwing parts at the problem.

I would also make sure there is nothing blocking flow at the sea cock, strainer, and discharge lines. Shells can I grow and get dislodge resulting in aggravating random restrictions.

Since they all share a single pump, When that unit shuts down, assuming the other are still running, do you still have flow out of the discharge of that unit?

 

[doc g]

Clean the heat exchanger with acid as I think tIM said ........Pat

 

[carolinacoast]

Limited Water flow over the coils is the likely culprit. Descale, kink in hose, loose hose clamp. Cracked manifold. All things that may have been checked.

 

[motoryacht lover]

Thank you all for responding. Jack I think you got it. I turned all other units off and ran just the problem unit. there was no water being pumped. Of course unit tripped on high pressure. I will set one of the units very cold tonight so hopefully that will keep the water flowing and problem unit (master stateroom of course) will stay cooling. I am amazed at the collective wisdom of this site. Thanks again everybody.

 

[saltshaker]

Thank you all for responding. Jack I think you got it. I turned all other units off and ran just the problem unit. there was no water being pumped. Of course unit tripped on high pressure. I will set one of the units very cold tonight so hopefully that will keep the water flowing and problem unit (master stateroom of course) will stay cooling. I am amazed at the collective wisdom of this site. Thanks again everybody.

Easy inexpensive fix you can do yourself.

 

[MikeP]

Sounds like a bad trigger for the Master SR system. The trigger box is in the room with the compressors. The triggers - one for each AC unit - turn the pump on when that ac unit is running. Last time I replaced one they were around 30 bucks. Takes maybe 10 minutes.

 

[carolinacoast]

Nice work. Buy 2 triggers and leave an extra in the box.