Air conditioning issue

Captain Mateo

Captain Mateo

.
Jul 31, 2020
33
Hunter 460 Annapolis
Yes, another post on air conditioning, but I am out of options and everyone here always comes through. My MarineAir (now Dometic) 12,000btu air conditioning stopped blowing cold air after a sail on Saturday. The one in my salon (16,000 btu) continues to work, but the aft one does not. Both run off the same March water pump. I did the three main troubleshooting tactics: 1) clean raw water strainer. 2) clean filter/coils for better airflow, 3)flushed the raw water line for better water flow. Still blowing room temperature air. The fan and compressor both come on. Because the compressor comes on, it makes me think it is not a relay or electrical issue. And if the refrigerant was low/leaking in the compressor, wouldn't it shut off and read a LPF on the display? Any thoughts or suggestions are appreciated! Maybe I am overlooking something.
 
kloudie1

kloudie1

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Nov 6, 2006
10,017
Hunter 34 Mandeville Louisiana
Check the connections on the "reversing" valve. There is a solenoid that reverses the refrigerant flow to provide reverse cycle heat. If that valve sticks , it can cause that.. Switch it to "heat" and raise the thermostat to make the compressor come on. Tap the solenoid (not too hard, but a little smack).. then set it to cool and lower the thermostat to start the compressor. (there usually is a time delay that won't let you restart the compressor for a minute or so) rap on the solenoid again a bit. If that doesn't do it, it's time to call the dude who fixes AC.
 
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Captain Mateo

Captain Mateo

.
Jul 31, 2020
33
Hunter 460 Annapolis
kloudie1 said:
Check the connections on the "reversing" valve. There is a solenoid that reverses the refrigerant flow to provide reverse cycle heat. If that valve sticks , it can cause that.. Switch it to "heat" and raise the thermostat to make the compressor come on. Tap the solenoid (not too hard, but a little smack).. then set it to cool and lower the thermostat to start the compressor. (there usually is a time delay that won't let you restart the compressor for a minute or so) rap on the solenoid again a bit. If that doesn't do it, it's time to call the dude who fixes AC.
Click to expand
Thanks @kloudie1 . Didn't even think about that at all but will give a try this evening. Already have a call in for AC guy, but they are 4+ weeks out. Good thing we arent going into July or anything... :biggrin:
 
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C

Capt Robbie

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Jan 24, 2017
669
Hunter 34 Toms River Nj
1) possibly air locked on that unit only and no water flow through the coil?
can you disconnect the water outlet side of the coil and verify that water is flowing thru the coil or not enough flow.
2) some older units had a reset button near the evaporator coil that may have tripped.
 
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Lee Hadjiosif

Lee Hadjiosif

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Apr 14, 2010
195
Jeanneau 42DS Larnaca Marina
With your setup, you should have one intake hose and two outflow hoses. Are both hoses running water to the outside or just one? You may have a balancing problem or a blockage if only one outflow is working. If both are working, is the volume of water coming out about the same? You may have a restriction in one of the hoses.
 
SEMPERAVANTI41

SEMPERAVANTI41

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Jun 15, 2012
715
BAVARIA C57 Greenport, NY
Did the A/C work before your sail? If it did, and your sure your compressor is coming on, I think your compressor is shot. You can try to install an inexpensive, easy to install "Hard Start" like a Supco SPP6E. I installed one on my forward A/C and it gave the unit another 2 or 3 years of use.
I also bet that the most cost effective solution is to replace the unit. I have replaced all 3 units on my boat, and have never been able to justify the cost of repair.
 
Captain Mateo

Captain Mateo

.
Jul 31, 2020
33
Hunter 460 Annapolis
Wanted to provide an update and solution to this for any future searches. First of all, thanks to everyone for their suggestions. Turned out to be a combo of two things. AC tech came and found this: 1) Compressor was empty of refrigerant (the new 410A stuff). Apparently compressor was heating up due to lack of refrigerant and tripping the thermal relay before showing a LPF (low pressure fault) on the display. Tech added 10oz; 2) The water flow out the rear through this unit was very slow. Even though I had flushed it with a hose during troubleshooting, it wasn't quiet enough. Tech hooked up a high pressure to the hose on the discharge of the March water pump and flushed the system. Brown stuff came out for a good 5 minutes.

Everything is working great now! Our only concern is where did the refrigerant go? Perhaps a small leak that will need to be monitored. The tech surmised it may need recharged once a year. But, hey that beats replacing the entire unit for $2-3K right? (oh yeah, and tech said if I wanted to go that route, systems aren't available until December due to supply chain and demand!)
 
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JamesG161

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,728
Hunter 430 Waveland, MS
Captain Mateo said:
Our only concern is where did the refrigerant go?
Click to expand
Did know that your compressor pumps many thousands of cycles per hour.
The Oil does breakdown eventually and normally filtered out.

But that filter restricted would cause the overheated state and shut you down.

Jim...
 
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DeniseO30

DeniseO30

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Feb 26, 2009
716
Oday 30 Anchor Yacht Club, Bristol PA
There are a few misconceptions here.
low pressure, low air flow, clogged filters on what is called the "low side" of an air conditioning system generally will not cause overheating of a compressor.
What did happen as mentioned. the condenser was clogged apparently with mud and algae, it was enough to cause excessively High "high side" operating pressure.
that would cause the compressor to heatup or work harder, it probably wasn't enough to set off the high pressure control but it would cause a higher low side pressure, making the system not cool.

AND, the technician probably added refrigerant because that is the one thing owners feverently want to hear and know! 10 oz is a very small amount just slightly more than is lost when gauges are connected and disconnected,
This way the owner has something to say to his friends like "yeah he just topped it off"

I've always considered topping the closest thing to a placebo pill a technician can offer a hot and frustrated owner! On older systems adding refrigerant can actually help cool the compressor motor windings.

Old school technicians still adhere to the conviction that saturated refrigerant gas returning to the compressor should cool the compressor which is no longer true of modern-day rotary and scroll compressors that can actually get damaged if slugs of refrigerant hit the internal workings, unlike the old piston compressors that could handle "flood back"
hope this helps and doesn't confuse everybody
 
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SEMPERAVANTI41

SEMPERAVANTI41

.
Jun 15, 2012
715
BAVARIA C57 Greenport, NY
Mateo, that's not a bad price for coming out to your boat. Unfortunately, what ever is leaking is probably still leaking. Maybe the charge will hold for 10 years, maybe it will leak out soon. There are many stop leak chemicals on the market that may work, does anyone have any experience?
 
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Crusty Ol Salt

Crusty Ol Salt

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Aug 19, 2021
504
Hunter 280 White House Cove Marina
SEMPERAVANTI41 said:
Mateo, that's not a bad price for coming out to your boat. Unfortunately, what ever is leaking is probably still leaking. Maybe the charge will hold for 10 years, maybe it will leak out soon. There are many stop leak chemicals on the market that may work, does anyone have any experience?
Click to expand
Bingo! borrow a leak detector and sniff the refrigerant side of things. A good place to start looking is that little oil spot on the joint.
 
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