Problem with two AC units

[Jolly Roger]

A problem has developed in my two Pompanette marine air conditioning units which is baffling me, and I hope someone with more knowledge will be able to suggest a remedy.
I will give a background as concisely as I can:
I have two identical 16,000 Btu marine AC units, one forward and one aft, fed by a single 120 volt water pump which splits to each unit. These units have run perfectly for three years. The water pump was submerged in a recent fresh water flooding, but I dried it out thoroughly, and it seems to pump as normal, and the flow through both outlets looks to be the same as it was before the submersion.
Afterwards both units ran as normal for about a month.
The recent problem:
The rear AC unit still works perfectly. But when I switch the forward unit on during the day it cools for about ten minutes, as I watch the voltage on my AC meter slowly rising, from a normal of about 11 amps, until it reaches 20 amps, then trips the 20 amps breaker, shutting down both units. Sometimes the forward unit just shuts down itself with a HPF reading, (high pressure fault), even before the rising amperage trips the breaker.
I then have to use only the rear unit, which is just keeping me sane, when it’s over 100F outside.
In the evening, (when the temperature in Florida is considerably less than during the day), both units run all night, the forward one only clicking the breaker as the ambient temperature rises in the morning.
Clogged condenser fins will restrict air flow and cause a HPF fault, but I have cleaned them with both compressed air and vacuum, and they don’t look any different to the aft unit fins.
The manufacturers told me a HPF fault is only caused by either a lack of water flow, or a reduced air flow. They cannot suggest why the amperage rises before it trips the breaker. It’s no good sending the unit back for inspection because they can’t refill it with R22, because the law has changed and they now use different freon.
One remedy would be to find a marine AC engineer, but being a cheapjack yachty, I thought I would ask here and see if I can fix it myself.

[belizesailor]

Originally Posted by Jolly Roger

...The manufacturers told me a HPF fault is only caused by either a lack of water flow, or a reduced air flow. They cannot suggest why the amperage rises before it trips the breaker. It’s no good sending the unit back for inspection because they can’t refill it with R22, because the law has changed and they now use different freon.[/SIZE][/FONT]
One remedy would be to find a marine AC engineer, but being a cheapjack yachty, I thought I would ask here and see if I can fix it myself.

Sounds like a water flow issue to me. Typically these result in an HPF fault. Very common for the hoses to get gunked up over time. If they are, then even a properly functioning pump wont push enough flow thru the restricted hoses. You can clean then manually with a small snake or similar and/or by filing the hoses with a mild vinegar solution and then flushing well.

[DeepFrz]

If you have not cleaned the water passages in three years then that is most likely the problem. The submerging etc. probably has nothing to do with the situation. Flush and clean each fresh water circuit separately by circulating a solution such as Barnacle Buster or other purpose made solution.

[damir s]

Try to disconnect outlet hose from fwd cooler to see if water going out but use bucket not fill bilges. If is not water flow on outlet check inlet in the cooler. if water going out from hose problem is in the cooler, if not check hose from pump to the cooler.

[captainjay]

Check the pump relay. If you turn on only the forward one are your sure the pump is running? I have seen the relay go bad and one unit will turn the pump on and the other won't. When the unit that is turning the pump on is running the other unit will work fine. If the good one cycles off it will HPF.

[dave948]

Reduced cooling capacity of the condenser will cause a rise in compressor head pressure which will cause the compressor to work harder, that accounts for your increased amperage. The pressure builds to a point where you are getting a high head pressure fault on the unit.
In basic terms two things cause high head pressure, low coolant flow or an overcharged unit. If you haven't added refrigerant lately it means you have a condenser flow problem.

[Jolly Roger]

Thanks for these replies fellas.
I’m not at the boat for another week, but I’ll try these remedies and let you all know.
I rather thought it might be a overworked pump, maybe due to a blocked forward delivery water pipe, so I’ll make sure the whole system is cleaned out when I get back.
I meant to ask. Does anyone know a way to actually clean any dust or muck out of the condenser fins? Mine are very close together, about 1mm, and the actual radiator is about 2 inches thick, so it’s impossible to see through to tell if any section is clogged. I’ve used compressed air to blow any muck through, and a shop-vac to try and suck it out—not at the same time of course. I’ve also carefully straightened any bent fins, so I looks okay, but how can you test or thoroughly clean such a thing?
JR.

[sailcrazy]

Another thing worth checking....and don't ask me how I know??? Check the condenser fins as the amperage ramps up or just after it pops the c/b and shuts down-is there ice forming on the fins? If so, that could well be your problem. It happens to our fwd aircon all the time. I just watch it and when I feel cold/ice forming I need to open/remove a couple of drawers or do something else to allow more air to get to the fins....and then it works fine! Must have something to do with the rel humidity and/or room air temp?

[transmitterdan]

The part that gets cold and air blows through is an evaporator not condenser. It can be cleaned with a vacuum if just dusty. Also, a bit of soapy water in a garden sprayer can be used. For serious dirt there are spray cans of foaming coil cleaners at most hardware stores. Directions are on the can.

The OP most likely has some buildup in the condenser (that's the part with seawater flowing through). This buildup prevents heat from the hot output of the compressor being removed. As the temperature increases so does the compressor current. Eventually either the compressor will stall or the high pressure limit switch will stop the compressor. Cleaning out the water loop will fix this problem 90% of the time. Sometimes all that's needed is a simple back flush. But vinegar may be needed to dissolve hard buildup.

Icing can be due to dirty coils or dirty air filters. Dirt blocks air flow and the water that naturally condenses will freeze if the air flow is restricted. Another less likely cause of freezing can be low refrigerant volume due to a leak.

[DotDun]

Barnacle Buster - circulate thru the raw water circuit for 2 hours each AC.

5 gal bucket, bilge pump in the bottom, output connected just past the pump/manifold, capture the output line from the condenser and deliver back to the bucket. Mix BB per directions, 2 gals diluted mix is plenty to clean both ACs.

[captainjay]

Originally Posted by Jolly Roger

Thanks for these replies fellas.
I’m not at the boat for another week, but I’ll try these remedies and let you all know.
I rather thought it might be a overworked pump, maybe due to a blocked forward delivery water pipe, so I’ll make sure the whole system is cleaned out when I get back.
I meant to ask. Does anyone know a way to actually clean any dust or muck out of the condenser fins? Mine are very close together, about 1mm, and the actual radiator is about 2 inches thick, so it’s impossible to see through to tell if any section is clogged. I’ve used compressed air to blow any muck through, and a shop-vac to try and suck it out—not at the same time of course. I’ve also carefully straightened any bent fins, so I looks okay, but how can you test or thoroughly clean such a thing?
JR.

Foaming evaporator cleaner you can get it at any air conditioning supply house.


http://www.amazon.com/FJC-5914-Foami.../dp/B002EAKX88

[bstreep]

All good suggestions. Most likely cause is mineral buildup. As noted, barnacle buster or other acid flush should help the flow. It's also possible your pump is failing. Good thought on the pump relay too.


Sent from my iPad using Cruisers Sailing Forum

[170122]

Originally Posted by Jolly Roger

A problem has developed in my two Pompanette marine air conditioning units which is baffling me, and I hope someone with more knowledge will be able to suggest a remedy.
I will give a background as concisely as I can:
I have two identical 16,000 Btu marine AC units, one forward and one aft, fed by a single 120 volt water pump which splits to each unit. These units have run perfectly for three years. The water pump was submerged in a recent fresh water flooding, but I dried it out thoroughly, and it seems to pump as normal, and the flow through both outlets looks to be the same as it was before the submersion.
Afterwards both units ran as normal for about a month.
The recent problem:
The rear AC unit still works perfectly. But when I switch the forward unit on during the day it cools for about ten minutes, as I watch the voltage on my AC meter slowly rising, from a normal of about 11 amps, until it reaches 20 amps, then trips the 20 amps breaker, shutting down both units. Sometimes the forward unit just shuts down itself with a HPF reading, (high pressure fault), even before the rising amperage trips the breaker.
I then have to use only the rear unit, which is just keeping me sane, when it’s over 100F outside.
In the evening, (when the temperature in Florida is considerably less than during the day), both units run all night, the forward one only clicking the breaker as the ambient temperature rises in the morning.
Clogged condenser fins will restrict air flow and cause a HPF fault, but I have cleaned them with both compressed air and vacuum, and they don’t look any different to the aft unit fins.
The manufacturers told me a HPF fault is only caused by either a lack of water flow, or a reduced air flow. They cannot suggest why the amperage rises before it trips the breaker. It’s no good sending the unit back for inspection because they can’t refill it with R22, because the law has changed and they now use different freon.
One remedy would be to find a marine AC engineer, but being a cheapjack yachty, I thought I would ask here and see if I can fix it myself.

Your unit is building up calcium inside your water cooled condenser, it will be necessary to do a descaling, please do not use muriatic acid, search in Google for a good solution, we use barnacle busters but follow the instructions, concentrated will not work, we use 5:1 on a bucket and our oil Change pump once a year, we use soap and water to rinse the pump. You have to create a loop circulating the solution for about 10 minutes,

[170122]

Originally Posted by Mabruteam

Your unit is building up calcium inside your water cooled condenser, it will be necessary to do a descaling, please do not use muriatic acid, search in Google for a good solution, we use barnacle busters but follow the instructions, concentrated will not work, we use 5:1 on a bucket and our oil Change pump once a year, we use soap and water to rinse the pump. You have to create a loop circulating the solution for about 10 minutes,

Pump relay will not be the issue.. Try to run each unit independently, if the pump run the pump relay is ok.

[sailnow2011]

HPF= not enough cooling water
LPF= not enough air flow.
Your AC most likely needs to be descaled. Try vinegar. fill the tubes with it, and let it sit.