A/C stops A/Cing....

[650Guy]

So project 1 of 5 done and now I’m on to my A/C issue and would love all your input as honestly, it’s been invaluable!

Here is what I’m seeing:

* ac will fire up and run swimmingly for an hour, may even 3 or 4 hours... but then it stops. The fan still blows, and according to the panel it’s calling for cold air, but the water pump turns off and no cold air??

My first thought is the water pump is bad, and once the pump stops the AC shuts off, but I get no HPF error or anything.

On a side note, it has always struggled to switch between heat and cold. Not sure if that plays into it or not. I’m grasping here but thought maybe the reversing valve is bad?

To me the key factors are:
* it’s calling for AC
* no water flow
* works fine for a while then just stops doing its job

Any idea of where to start? Are these units repairable or is it usually a remove and replace type situation?

Thanks all!!

[Midnightsun]

My guess is the relay that activates your water pump is acting up. No water flow will definitely stop the cooling process. Some brands are an easy off the shelf fix while others require an expensive proprietary board. Not sure what you may have.

[650Guy]

Oh that would be a good fix! I’ll be back at the boat in a day or two and will find out the specific unit.

[Midnightsun]

If you are handy with electricity then just connect the pump directly to 110v and run the AC like you normally would. If it keeps cooling then the relay is the issue.

[650Guy]

Just skimmed through the owner’s manual and do not see a control board for the seapump. Could it be located inside the pump itself?

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[650Guy]

Yep. Totally get what your saying about bypassing it and just running it via 110. I’ll work on that when i get there.

[BenTen]

What boat and most importantly, what kind of controls (3 knob or digital)?

[tomschauer]

If the pump turns off and the compressor turns off at the same time it sounds like a control issue. If you have one of the digital displays and its not showing an error, the pump and compressor is most likely being commanded off. Could be as simple as an offset being programmed into the control.
If you set it to 72 degrees f, how cool does it get before it shuts down?
Look up the manual and check offsets and auto changer set points. Also many units have a coil temp sensor that will shut off the compressor to keep the coil from freezing. If you have one and it is tripping, most likely a very dirty coil or something else restricting air flow.

[650Guy]

So my boat is a 2001 350 Mariner and yes it has digital controls. It has 3 lights that tell you what its doing that look like dash's next to the temp:

- AC
- Fan
- Heat

So times that it will fail, the fan continues to run, the temp will increase, and the light for AC will illuminate, but the sea water pump will not turn on, and AC unit never turns on but fan will and the AC Light will illuminate. and NO error code.

USUALLY when I first arrive at the boat, it all fires up normally and works for a while.. but the longer I'm there and its running, I get issues.

[vineyardgray]

My boat has the pump wired to run all the time, so bypassing the control circuit permanently is an option for you, although I suppose it is wasteful of electricity.