High PS

Russ Calasant

Russ Calasant

Active Member
Dec 9, 2009
2,128
East Greenwich, RI
Boat Info
2001 480 DB
Engines
CAT 3196
I'm sure it's been talked about however I have been unable to find what I need. A new AC unit running off the same pump as two others went into high ps mode and shut down. I checked the strainer and found it in need of cleaning. Following the cleaning it continues to fault, the other two are fine. I also checked connections at the sensor on the AC. Any ideas?
 
Hi-PS is the code for high head pressure on your compressor. That is almost always caused by the compressor not being adequately cooled. If the strainer is clean, have you ever cleaned the system with acid to remove lime deposits and marine growth? I know the compressor is new, but the blockage can also be in the lines leading to or away from the unit.
 
Okay, sounds like the consensus is acid flush! How do you do that? - being only one of the three on that pump, new and the other two are not having an issue could it be anything else?
It certainly can't hurt and probably needs flushing. Just pour the acid into the strainer like antifreeze? Or do they make something?

Thank you - all btw
 
I found a bunch of old threads - sounds like phosphoric acid is the best. I'm still not exactly clear on a method. Circulate or pump through and let sit? I don't quite have a handle on circulate. Find an adaptor to enter in before strainer, find the exit hose on the manifold to complete the loop and make a bucket/pump. Pinch off exit hoses individually and circulate?
 
I wouldn't mess with trying to recirculate the acid. Phosphoric acid is cheap....Look for a product at Home Depot ot Lowes called Prep 'N Etch by Kleen Strip. Mix 2 gallons or acid with 2 gal of water and run it into the system with the circulating pump. I installed a T in the line between the seacock and strainer, added a ball valve and a hose fitting then put a bulkhead fitting in the bottom of a 5 gal bucket. Put the acid in the bucket, add the water then position the bucket above the strainer. Turn on the AC, close the seacock and run the entire contents of the bucket into the system. When the system sucks air thru the bucket, turn off the AC. Wait 10-12 minutes. Hook a water hose from your dockside freshwater source to the hose fitting while you are waiting, then flush the acid from the system with freshwater.......let the freshwater run a while to flush the acid.

Hope that helps........
 
Russ

Here is how I did it using the prep and etch at Home Depot. I got a Home Depot bucket and an old bulge pump that still worked. I installed the bulge pump in the bottom of the bucket with a fitting leading to the outside and I caulked it good. Then I installed another fitting near the top of the bucket. I added a short piece of 5/8/ garden hose to the bottom fitting and ran that to wash line that needed flushed. Then used cheap 5/8 clear vinyl tubing to go to the other end of the hose from each seacock. I flushed each line for 1 hour and it works like a dream!
 
Just curious...hows the flow out of your thru-hull fittings? There is a manifold that diverts water from the pump the the 3 units. I noticed one of my exits wasn't doing so well, so I found which one was the port at the manifold. There are 4 parts to it. 1-manifold, 2-line from manifold to unit, 3-unit, and 4-unit to hull. Try flushing each one and see what comes out. You may not need acid. I used a dock hose at first and then a 5gal bucket with two pieces of hose on an old fresh water pump. Circulated with simple hot water and that got things clean. THEN you may need to go with acid. Your blockage may just be at one of the ends and you can poke it free with some solid core copper wire like I did. Anyway...my $.02.
 
You could have a trigger switch that has gone bad. I suggest you run one AC at a time and confirm the AC water pump is providing flow. Turn off all AC units, turn one on and check for water flow. Then turn that one off and turn another on and check for flow again.

If one doesn't turn on the water pump, then you need to replace the trigger switch, about $60 and an hour worth of time.
 
CaptRonn said:
You could have a trigger switch that has gone bad. I suggest you run one AC at a time and confirm the AC water pump is providing flow. Turn off all AC units, turn one on and check for water flow. Then turn that one off and turn another on and check for flow again.

If one doesn't turn on the water pump, then you need to replace the trigger switch, about $60 and an hour worth of time.
Click to expand...

This is exactly what happened to mine last year. The trigger on the relay had gone bad so my stateroom thermostat could not start the pump on it's own.
 
CaptRonn said:
You could have a trigger switch that has gone bad. I suggest you run one AC at a time and confirm the AC water pump is providing flow. Turn off all AC units, turn one on and check for water flow. Then turn that one off and turn another on and check for flow again.

If one doesn't turn on the water pump, then you need to replace the trigger switch, about $60 and an hour worth of time.
Click to expand...
Good to know, thank you, I will check.
 
An interesting update. I flushed some acid through the system and saw some sediment but not as much as I expected. So after buttoning up and cranking up the pump and ACs I heard a very loud clicking noise in the mid bilge, there was some serious arcing occurring in the rear of the March raw water pump! Shut off power, inspected and quickly flipped on power to check again to more of the same only with some flames this time! I removed and replaced the pump and all ACs are functioning fine for the past couple hours so we will see. Not sure which fix or if both contributed but it seems problem solved. I can't help wonder if the pump fire was a coincidence and a lucky break or more likely caused by something I did?
 
Very lucky, I would check the thru hull and hose running to strainer and then pump. If these are clogged up, it would cause the pump to run hotter than normal. We, here in the south fight this all summer.
 
From what I understand, low ps is a Freon issue. Have you made sure the coils and filter is clean on the unit? Is it freezing up with ice?

Josh
 
NotHerDecision said:
From what I understand, low ps is a Freon issue. Have you made sure the coils and filter is clean on the unit? Is it freezing up with ice?

Josh
Click to expand...

Hi Josh, it was freezing up and relatively clean. I believe the unit is on its way out - compressor is loud and not very affective on cool either but functional. I had it serviced not long ago. I'm afraid I just have to bite the bullet.
 
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