AC problem

I have a ST 44 2015. Having problems with the berth AC units. About once a week I have to bleed the air out of the pump. The units go down on HI/PS. Anyone have ideas for a solution. I heard evaporator or condenser cores may be the issue. Not sure why when I bleed the pump the units work for a while?

Similar issue with one of my main cabin AC's.
Going to clean/flush soon as the WX breaks.
Did you clean the filter?

Back pressure due to fouling on the coil can cause the air in the system problem. Flush with Barnacle Buster or similar.

David

Yes I did clean the filter, I am going to try the flush.

QUOTE=SOJOURN4;635346]Similar issue with one of my main cabin AC's.
Going to clean/flush soon as the WX breaks.
Did you clean the filter?[/QUOTE]

One of my four units was doing the same. Going to flush with Barnacle Buster when I get a chance in a couple months.

Some additional advice from Dometic:

"I would recommend checking the wire connections at the high pressure switch to make sure they are secure to the pressure switch, and there is no corrosion which would cause a false reading. There should be two yellow wires connected to the pressure switch. Also, if you look in the electrical box, there is a green printed circuit board which will have the other end of the two yellow wires connecting to the high pressure circuit on the board. Make sure those connections are secure and no corrosion.

If all of the connections are good, and you have good water flow, you either have a true high pressure situation, or a bad pressure switch. You would need to connect a refrigerant gauge to the high pressure port to verify the pressure when faulting to determine if the pressure switch is good, or not.

You can jump the two wires at the pressure switch to verify all of the wiring is good. If the fault goes away, you know the wiring between the board and pressure switch is good. I would caution running it with the wire jumped, if the pressures are high it will continue to run due to removing the high pressure switch from the system. "

Any easy way to clean the filter?

Close sea cock
Remove intake line
Insert into 5 gal bucket (might need a temporary fitting/hose to extend)
Start AC unit
Run until fluid comes out of discharge @ hull
Turn off AC
Reconnect
Do same for other AC unit(s)
Get an adult beverage
After 6 or so hours open sea cocks and run AC for a bit to clean out Buster

Meant the air filter but I am going to flush all four lines this spring. The pumps will prime and suck from a 5 gallon bucket? Thanks!

Yes, did this a while ago and it fixed the problems I had with high pressure shut off. Used Barnacle Buster.

Mystery-
I CAREFULLY remove the fabric filter, wash off, let dry and CAREFULLY re-install.

Yes on the 5 gal bucket suction

So finally getting around to this. Are you sure its OK to run the solution through the raw water pump? It won't eat up the impeller or damage it somehow? I.e. breaks material loose and then it tries to run through the pump next time its started. That is the easiest way to do on the ST44 as I think getting to the discharge points to recirculate is a chore if even possible. Also, will the solution be "active" enough to keep cleaning if it sits 4-6 hours? I was thinking might be best to suck some solution in, let it sit for a couple hours, suck some more in, let it sit, maybe do one more time, just too make sure the solution is doing its job. Finally, how much barnacle buster did you need for all four HVAC units? Thanks!

An alternate method would be to close the thru hull, drain the system or vac/blow out as much seawater as possible, then temporarily connect hoses to each of the condenser coils in turn, creating a recirculating circuit with a bucket as a reservoir and a utility pump to circulate the cleaner through the coil for a period of time. That operation would be completely contingent on accessibility to each unit, but it would probably be a more effective cleaning method.

You won't be cleaning the other piping, but that could be treated by leaving solution standing in the piping. The objective is the condenser coil, since the mud /growth on that interferes with the heat exchange more than the flow.

I have done what you said just take the lid off the strainer and pour in your Barnacle Buster or muriatic acid let it run long enough till you think the solution is in the coils and then shut off. When you start back up watch you through fall she will probably see that the junk come out

We have a similar problem with our ac raw water pump. P.O. said to shut off raw water intake when underway as bubbles come in when moving. It seems the pump is not far enough below the waterline to self prime. So we close the thru hull before leaving the slip and reopen on arrival. No problems. No clear if this is your problem, but you could give it a try.
Gary

GGroves said:

We have a similar problem with our ac raw water pump. P.O. said to shut off raw water intake when underway as bubbles come in when moving. It seems the pump is not far enough below the waterline to self prime. So we close the thru hull before leaving the slip and reopen on arrival. No problems. No clear if this is your problem, but you could give it a try.
Gary

Click to expand...

What type of intake do you have?

One should be able to use their HVAC while under way. I have needed to use both heat on very cold days and AC on very hot days.

mystery said:

So finally getting around to this. Are you sure its OK to run the solution through the raw water pump? It won't eat up the impeller or damage it somehow? I.e. breaks material loose and then it tries to run through the pump next time its started. That is the easiest way to do on the ST44 as I think getting to the discharge points to recirculate is a chore if even possible. Also, will the solution be "active" enough to keep cleaning if it sits 4-6 hours? I was thinking might be best to suck some solution in, let it sit for a couple hours, suck some more in, let it sit, maybe do one more time, just too make sure the solution is doing its job. Finally, how much barnacle buster did you need for all four HVAC units? Thanks!

Click to expand...

Alright this turned out to be a lot easier than I thought! At least so far...

I was able to access the output side. I removed hose from thru-hull, purchased a barbed tee that took 2x 5/8 and outputted 3/4. Ran hose into bucket. Next I jumped the dometic box L1 pump to L1 breaker by simply moving the connection on the terminal. Finally I removed the tubing from the seacock, got a barbed 3/4 to 3/4, added some 3/4 hose, primed with a bottled of water, flipped on breaker, put into bucket with solution, and its running now. Important to make sure the tubing doesn't get stuck to bottom of bucket and create suction.

Dometic said it is fine to use the HVAC pump to circulate and my thought is there is probably growth within it as well so a good idea to include it in the flush. Dometic were the ones that said not to let it sit in the system and to circulate it while both Barnacle Buster and Rydlyme think its fine. I decided to go with Barnacle buster since it was readily available at westmarine in concentrated form and I got a discount. I could not find Rydlyme locally and by the time you add in shipping expenses it cost more than BB. I also considered using CLR, Heavy Duty D-scaler, and some other generic products, as well as making my own. Originally I thought I needed $300 worth of BB to flush all four of my HVAC, two engines, and genset but I'm told it might last a lot longer than I think. For now, I am using one gallon of BB concentrate for all four HVAC and will dispose as I plan to do the engines and genset next year.

The bucket turned dark and dirty within the first minute. I plan to run for 3-4 hours on each unit but good news is I only have two pumps so only have to do the flush two times to cover all four HVAC units. If I do yearly, I will probably run for 1-2 hours next time. I will try to post up some pictures later.

In retrospect I probably could've / should've done both at once... just needed an extra tee etc...

Greetings,
Mr. m. "...just needed an extra tee etc..." Here ya go!

MYSTERY -

How did you do the forward and mid berth AC units?

SOJOURN4 said:

MYSTERY -

How did you do the forward and mid berth AC units?

Click to expand...

Same as the salon units.

Disconnected the outputs, used a tee, ran a long 3/4" hose into bucket, extended input to pump using barb into bucket, jumped circuit, primed pump, and ran.

Next time in addition to doing all the units at the same time, I will probably plumb in a drain so I can put a bucket somewhere under the hoses.