A/C issues

They call me Tim

They call me Tim

Member
Jul 8, 2020
39
Boat Info
2011 280 Sundancer. We cruise on Lake Michigan out of Portage.
Engines
Mercruiser 8.2 Mag w/Bravo III drive
My new-to-me Sundancer has an air conditioner that runs off of shore power. We've been running it quite a bit in the few weeks that we've had the boat and it has worked well.

Yesterday, I noticed it had stopped cooling the boat. It would run and cool air would blow out for a few minutes, then a countdown would start on the A/C panel, the fan would blow, but there would be warmer air. It would cycle on again after the countdown and the air would blow cool again.

This cycling will repeat a few times, then I will get an error on the panel that says HI I5 or HI IS and the A/C will shut down completely.

Water is pumping through the system because I can see it coming out of the side of the boat when it's running. I found a small mesh filter on the front of the A/C unit that covers the fins and it is pretty dirty. Could that be the culprit, or am I looking at something bigger?

Thanks in advance for your help. There's a lot to learn on a boat like this that has a lot of systems on it. I just graduated up from a bow rider that didn't have any of this stuff.
 
They call me Tim said:
My new-to-me Sundancer has an air conditioner that runs off of shore power. We've been running it quite a bit in the few weeks that we've had the boat and it has worked well.

Yesterday, I noticed it had stopped cooling the boat. It would run and cool air would blow out for a few minutes, then a countdown would start on the A/C panel, the fan would blow, but there would be warmer air. It would cycle on again after the countdown and the air would blow cool again.

This cycling will repeat a few times, then I will get an error on the panel that says HI I5 or HI IS and the A/C will shut down completely.

Water is pumping through the system because I can see it coming out of the side of the boat when it's running. I found a small mesh filter on the front of the A/C unit that covers the fins and it is pretty dirty. Could that be the culprit, or am I looking at something bigger?

Thanks in advance for your help. There's a lot to learn on a boat like this that has a lot of systems on it. I just graduated up from a bow rider that didn't have any of this stuff.
Click to expand...
A dirty Filter can cause a hi pressure condition which will cause the hi pressure switch to shut the compressor.
 
The error could be from overcharged system (unlikely), poor water flow (most common) or poor air flow (ie dirty filter). The filter has to be really pretty cruddy on these systems to trigger a fault. Also make sure all your ducts to supply air to the system and cold air out from the unit are free. I would also not eliminate the possibility that your water supply to the unit is not sufficient. It should be a strong flow out of the boat, not a trickle. Check your strainer. Also, as we're in a heatwave now, don't set the unit on a super low temperature so that it is running continuously. Go down gradually, allowing the unit to cycle off occasionally as you get colder air throughout the boat.
 
How do I find the strainer?
 
They call me Tim said:
How do I find the strainer?
Click to expand...
Find the pump, probably in the engine room, and the strainer will be between it and the thru hull. If you haven't looked at that, I'll bet you find it's algae, barnacles (not sure, no location in your sig), or both. this time of year is the worst, no matter where you are.
 
370Dancer said:
Find the pump, probably in the engine room, and the strainer will be between it and the thru hull. If you haven't looked at that, I'll bet you find it's algae, barnacles (not sure, no location in your sig), or both. this time of year is the worst, no matter where you are.
Click to expand...

That's very helpful. The filter on the A/C unit itself was filthy. I'm sure airflow across the coils was restricted. I'm going to pull the strainer and clean it up. I know water flows through the system, but it might be restricted.
 
Welcome to CSR. A little preventative maintenance will go a long way. Systems in boats undergo a ton of stress. From the continuous vibration and pounding to the damp and salty exposure. If it is dirty from whatever reason; neglect / use / time - clean it. Dirt, crud, corrosion, loose connections are one of a new (used) boat owners worst enemies. Go through your boats systems one at a time and clean up anything that needs it. Check that connections are tight and not corroded. By being proactive in doing this, you will be way ahead of having to figure out issues in the middle of enjoying a day out. Make sure anything you use to repair or replace is marine grade, i.e. stainless, etc.
 
I cleaned out the strainer and the filter and I'm still having the same issues. I turned on the a/c and it pretty quickly dropped the temperature 10 degrees, then it cycled off to HI PS.

Water is flowing through the system and coming out of the side of the boat. Any thoughts?
 
Do you have 1 or 2 ac units in that boat and do you have more then one outlet? I ask because the system is a common system so if you have multiples then water will just take the path of least resistance. I pretty much think you still have a water flow issue. It may be pumping some but not enough to keep the unit from having too much pressure. I recommend you clean the water lines with dock water then acid.
 
Only one a/c unit, so I think there's really only one path for the water.
 
They call me Tim said:
Only one a/c unit, so I think there's really only one path for the water.
Click to expand...

Your water flow is reduced. You need to blow the line out. I do mine by hooking dock water just after the AC pump, then turning on the water valve and blasting the line. You’ll see all sorts of crud coming out.

These AC’s are sensitive to any lack of water flow. Just a coating of algae in the lines is enough to create the problems you are seeing.
 
CaptRonn said:
Your water flow is reduced. You need to blow the line out. I do mine by hooking dock water just after the AC pump, then turning on the water valve and blasting the line. You’ll see all sorts of crud coming out.

These AC’s are sensitive to any lack of water flow. Just a coating of algae in the lines is enough to create the problems you are seeing.
Click to expand...
Excellent! That kind of advice is exactly what I was looking for. You hook the dock line up after the water pump that's after the strainer in the engine room? That won't damage the a/c unit?

Also, someone said bromine tables in the strainer filter will help. Have you heard of that?
 
They call me Tim said:
Excellent! That kind of advice is exactly what I was looking for. You hook the dock line up after the water pump that's after the strainer in the engine room? That won't damage the a/c unit?

Also, someone said bromine tables in the strainer filter will help. Have you heard of that?
Click to expand...

Look in the engine room for the AC pump. It’s a 120v pump. Take the hose off of the output side of the pump. Buy one of these brass hose disconnects from a hardware store

index.php


Insert the small end in the hose, and clamp with a hose clamp. Put your hose on it, go outside to the dock and turn on, and watch the outlet. You’ll see all kinds of gunk come out. Give it several on and off blast till it’s clear.

From the dometic manual:

The Effect of Seawater Temperature
The efficiency of the system is dependent on both the seawater and cabin temperatures. In cooling, the air conditioner works
best when the seawater temperature is below 90°F (32°C). At higher water temperatures the unit will operate, but at reduced capacity. As the water temperature rises, so does the refriger- ant gas pressure. A high-pressure safety switch will shut the unit down if the water temperature gets too hot, or there is a loss of cooling water flow.
In heat mode, the opposite is true. As the seawater tem- perature gets colder, there is less heat available and heating performance drops. Full heating capacity is available in water temperatures as low as 55°F (13°C), but drops to about 50% capacity in 40°F (4.4°C) water. Below this, the refrigerant pres- sure can be so low that the unit will not produce heat, (or may shut down on low-pressure fault, if this option is installed).
 

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On bromide, I don’t have anything. I’ve never used it and don’t know if it could possibly damage your AC unit.

Right now we are having high seawater temps. Around my boat the water temp is 94 degrees. As you can imagine, this just works the AC even harder.

So a slightly dirty water line coupled with a high water temp will trigger the high pressure shut off.
 
We don't have the high water temps on Lake Michigan, but I'm sure you are right with the algae growth in the lines. I'll give that a try.

I think I'll also try to find some bromine tablets (Amazon?) and see if that helps. It should kill off the algae.
 
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