cruise/air problems

[spincycle]

Getting a hi P S on the digital read on one of my a/c units. i turn on the unit, the compressor starts in about 20 seconds after initial buttons are pushed, look over the port bow and the unit is pumping water outside. then in about 3-5 minutes the error code Hi P S shows up. no more water being pumped over board, and the unit has shut it self down. any ideas?
An other unit on board did a LOW PS the other day on me too, and it will not stay running much past 3-5 minutes also.

Spincycle

 

[Boatsb]

Sounds like a pump problem. Check if the units are getting hot while the pump is running. If so is it pumping all it should?

3 things for the compressor to be shut down other than the thermostat.

1) Temp sensor
2) pressure sensor High
3) Pressure sensor low.

If it was running fine and has not been worked on or charged it is very rare for it to really be shutting off from high pressure. has anyone done anything to it lately?

 

[spincycle]

the boat has been idle for a year before Pascal and i ran it to Tampa from GA. one owrk had been done to the a/c units but it was out for a bottom job for 1 week when she was in Shavanna GA. they said every thing was re-primed. low on freon a possiblity? the problem started when we went to use the A/c's once getting to Miami. The heat portion of these units can be used no problem and no error messages on the display, there are six a/cc units on the boat and only two are giving me this type of error problem.

Spincycle

 

[spincycle]

to clarify, no work has been done on the units.

Spincycle

 

[Jaxfishgyd]

AH the "old cruiseair" problem.... use the 'search' feature on this site and you will get a LOT of info..... Trust me... "been there, done that, have the shirt"...

 

[Boatsb]

Could be high temp from low freon. The units cool the motors with the return liquid freon. If that is the problem a set of gages should be able to show you the problem.

 

[krush]

if hi PS means high pressure trip you could be over charged or have a dirty condenser.

Low Ps could mean either a low charge or dirty evaporator coils.

You need a set of gauges and a thermometer to know what's going on. I created this thread awhile back: http://www.samsmarine.com/forums/showthread.php?t=7126

I've fixed lots of A/C's before.

 

[Pascal]

it's not a pump problem. The boat has two pumps and both were running with good flow, triggered by other units. the only water flow related thing could be an obstruction in that specific unit but i dont' think it is. the water hose was cool, even though everything was hot in the genny room, indicating flow.

Now the other one (which one? there was a temp. PS on the Mid ship too) coudl be a flow problem, check that. First make sure you have good discharge, then when the genny room is hot after a run, check to see if that hose is cool. Or unclamp the end of the hose on the discharge side of the AC,put it in a bucket and turn it on.

otherwise, the first thing to check is indeed charge by putting a set of gauge.

the thing is that it worked fine in Reverse cycle... could it be the Reverse cycle valve sticking or does it just happen when heating? Would low pressure not affect heat mode as much ?

I have no experience troubleshooting ACs when it comes to reverse cycle!!

 

[Boatsb]

Check to see that the water is cooling the coils. There should be a big temp difference in the incoming and out going temps. Also check the individual hoses and coils for blockage. Beyond that the gages are needed. If everything is getting ample water and the lines are clear allowing flow and cooling ( not encrusted with marine life) it's either a refridgerant level issue or a bad sensor ( never had an electronic part give me a wrong reading yet )

 

[Pascal]

"Check to see that the water is cooling the coils. There should be a big temp difference in the incoming and out going temps."

not going to be since the compressor doesn't run long enough for heat to get transfered.

 

[Boatsb]

If it only runs a few seconds I would guess low pressure/refrigerant.

 

[krush]

A fouled condenser could cause high pressure (aka dirty condesnor). Depending on the severity, it only takes 10-20 seconds of no heat transfer to shoot the pressure sky high.

Also, there is the other unusual problems like a stuck TXV or a stuck check valve. It may work in heat pump mode because the cooling TXV is bypassed.

Overcharge is a possibility too. If some do it yourself charged it to XXX psi (like people on this forum say to do) on the low side on a cool day, when the ambient warms up, you can shoot the head pressures through the roof.

You need gauges and need to know how to interpret them.


Hey pascal, I thought boats didn't have reverse cycle units?

 

[Pascal]

Hey pascal, I thought boats didn't have reverse cycle units?

 

[Pete]

Bottom line, it sounds like a heat transfer problem in the water cooled exchanger mounted on the compressor base unit. The over pressure is caused when the high side liquid refrigerant does not accomplish sufficient heat transfer to another medium. Heat transfer is a function temperature differential and conductivity of the heat exchanger material. When in cool mode the water cooled exchanger gets hot and needs to be cooled by transfering heat to the cooling water. In your case, lets assume that the conductivity is a constant (since nothing has changed on your system). When you were in cooler waters the temperature differential was greater, thus heat transfer was apparently just sufficient. Now in south Florida the water temperature is much warmer, the differential is much less and insufficient. This is the same situation that causes Detroits to over heat quicker in summer in the south, versus the northern waters. You need to clean your water cooling heat exchanger water passage and be sure that the hoses that supply and discharge the cooling water are free of any materials. You need to be getting 250 to 500 gallons an hour through the exchanger passage. In south Florida, the closer to 500 the better. On a long term plan, this condition is probably caused by the plumbing holding water in the exchanger water passage when the unit is not running. Anything you can do that will cause the unit to be self draining when off will aid in not dealing with this problem in the future.

On your low pressure shut down, this is 99.99% of the time a low refrigerant charge. As suggested before, get some gauges and charge the unit to the values on the Cruisair charts in the owners manual before doing anything else.

Pete

 

[Jaxfishgyd]

Hey pascal, I thought boats didn't have reverse cycle units?

Oh God..... This is the type of person who might actually vote this year.....

 

[Traveler 45C]

I concur that the cooling hoses and water passages are probably coated with marine life or are just really dirty. That’ll reduce water flow enough to shut down the A/C’s. It’s very easy to clean the coils, see http://www.samsmarine.com/forums/showthread.php?t=1483

Since she was sitting so long cleaning the coils and replacing the hoses is a good idea, ‘speacially in Fl in the summer. You’ll need all the flow you can get.

You don’t want to be at anchor, in the summer and in a 130f degree engine room trying the work on the A/C’s, I know. It’s NOT fun!

 

[fixin-to-cruise]

The simple way to diagnose this is to shut off all the other AC units and select cooling mode on the one that is giving the H!/PS shutdown message. Just look at the cooling water discharge out the side of the boat and see if it looks normal. I'll bet it is either off or weak, probably off.

Here's the Cruisair SMX manual info about HI/PS shutdown messages scanned from the Cruisair "SMX Microprocessor Air Conditioning Control" "Owner's Operation Manual":

HIGH PRESSURE SHUTDOWN: This feature is available if the high pressure switch is used. Specific reaction to high pressure depends on whether the system is in the cooling or heating mode. In the event system head pressure rises above 400 to 425 PSI in the cooling mode (usually the result of loss of cooling water flow) the SMX will initiate a sustained shutdown of the entire system and alternately display HI followed by PS. This code means the system pressure rose above the set limit. This is a sustained shutdown and, even when the pressure falls after shutdown, the system will remain off until reset by pressing the OFF key. In the heating mode, a rise in head pressure above the set limit will result in a 2 minute compressor off period to allow the heat in the coil to dissipate which readies the system for recycling in the heating mode. Cycling based on input from the high pressure switch will continue until the room temperature reaches setpoint, after which, compressor cycling will be automatically transferred to thermostat control.

Good luck and let us all know what it was!!!

 

[Pascal]

"The simple way to diagnose this is to shut off all the other AC units and select cooling mode on the one that is giving the H!/PS shutdown message. Just look at the cooling water discharge out the side of the boat and see if it looks normal. I'll bet it is either off or weak, probably off."

not really because you have multiple units on one water circuit so when the pump runs it sends water thru all the condensing units whether they are on or off. If you have a blockage in that condensing unit or its line, the overall flow will be pretty much the same no matter which one is on. There are no valve that stops the flow of water when a condensing unit is off.

 

[Trojan]

Why don't you just clamp the hoses off to the other units and watch the water flow through each unit. A C-clamp and 2 pieces of wood. The heat exchanger on a cruisair AC is not a tube bundle. It is like bundle of little troughs quite strange. It must cost a bundle to make. No condenser and fan.

BILL

 

[spincycle]

well had my a/c guy on the boat today( glad he is on my payroll) for about 6 hours. put a set of gauges on every unit on the boat and found some units low on freon, and some that were over filled with freon. found most of the filters next to the condensing units pluged or nearly pluged with matted lint. cleaned all coils, filters and leveled out all the freon levels in all units. everything seems to be cycling and running fine. pascal had said it and i will too, the cooling water flow seemed good in all units. but flow did stop when the unit reads either hi PS or Low PS and shut it self down. so far it looks like freon levels and very dirty filters are to blame.

Spincycle