Marine Air Systems A/C

[Doorpro]

Originally Posted by mannix2

Try replacing the HPF circuit breaker. I just went through the same issues and oddly enough that resolved the problem. The HPF breaker tripped randomly and repeatedly. One day I pushed the "Push to Reset" breaker and it did not spring back out. After replacing the breaker two months ago, absolutely no problems. Inexpensive solution if works for you. Circuit breaker cost about $10 from West Marine, or $6 from Amazon.

This is a new one for me, I obviously changed over the digital control with one from another stateroom and the problem persisted. Can you please emlighten me as to where I might find the breaker that you're mentioning because for $10.00 I'll change it, just because I can.

regards,
Doug.

[transmitterdan]

On your unit there is no lockout switch. It is all software driven. Also, it should give a different indication for LPF and HPF. Have you verified the indication is indeed high pressure and not low pressure?

[Doorpro]

Originally Posted by transmitterdan

On your unit there is no lockout switch. It is all software driven. Also, it should give a different indication for LPF and HPF. Have you verified the indication is indeed high pressure and not low pressure?

It definitely flashes HPF... I know nothing apart from how to plumb and wire the thing and of course the ducting. Lets face it they're simple to install and the other AC unit which sits right next to in in the same drip tray (they're over a hallway) is perfect. If it is indeed a Freon problem then I shall have to call someone but to be honest if it does persist I may change the control boxes over and see if that makes the other go bad. I have alternated the digital switch on the walls and that changed nothing.

regards,
Doug.


PS. The unit has now been running for two hours without fault

[DeepFrz]

My apologies. I got two threads on the same subject confused in my head and part of my last post was about problems in the other thread.

I'm glad your system is now working well.

[Doorpro]

No problems but we've seen this before. It will work great for a day or two and then act up again. I really did nothing this morning apart from take stuff apart and put it back together so I'm sure that I still have a problem.

[rassabossa]

I really did nothing this morning apart from take stuff apart and put it back together

Funny, I've done that before too and had things work...and sometimes they never worked again.

[transmitterdan]

I doubt it is the control unit. HPF is caused by a pressure switch that clicks when the high pressure side exceeds a preset. The switch automatically resets itself. I believe this unit has a separate switch for the low pressure fault.

I agree with a previous poster that gauges might reveal the true problem. It may be a bad switch or it may be some component in the system is intermittently clogged up. These intermittent problems are a real pain. Suggest you discuss it with a marine A/C guy and see what he thinks.

[CarlF]

I picked up one of these at a boat show. Haven't used it yet but it sure should make flushing A/C lines easier. Your city water test isn't conclusive since there could be hard barnacles or a crimp in the lines. The water would still run clear. If you put a bucket under the outflow and measure a minute of water, is it well above the amount of water in the Marine Air spec?

Sea Flush

I think your "clue" that it happens in hot weather may be important. A/C systems are a careful balance between cooling water, refrigerant, and air flow. Humid air is much harder to cool (2/3's of A/C energy goes into dehumidifying not cooling)

The new units you bought are probably very different from your old ones including a new refrigerant (410A). So you have to consider almost every source of trouble.

HPF failure can be set off by airflow restrictions. The new units may need more return air and supply air than your old ones.

And it could be refrigerant. You may have a borderline undercharge or overcharge that trips the alarm condition in hot/humid conditions.

[CarlF]

Next time it happens, run it on fan only while the other units cool down the boat. After an hour or so of the cooling see if it will run without an HPF fault. That would narrow your range of culprits

Also, if it happens again, turn it on for just a minute or two and then it off before and HPF. Do this a few times with 10 minutes or so in between runs.

[pbbmorton]

If you haven't flushed the units since installed they are way over due. Just circulate muriatic acid thru each unit until it comes out clean. Highly likely this is your issue. Even if not, they are way over due. Depending on use flushing should be an every two years plan.

Sent from my SM-G900T using Cruisers Sailing Forum mobile app

[Canibul]

I doubt ours has been flushed in 30 years. How long do you let the muriatic acid sit in the system? I can't easily catch it when I hook up the water again, it vents under the bridge deck of a catamaran.

[Doorpro]

It is now almost 5:00 pm here in SoCal so my AC has been running all day since about 9:00 am and all I did was check for a blockage. I'm sure that it will play up again soon and then I will flush it.... Go figure!

[Doorpro]

I'm guessing that I will need a bucket, a couple of hoses and a small bilge pump and let it cycle through. Any thoughts?

[captainjay]

It is also entirely possible that the High Pressure switch is bad.

[Canibul]

I'm planning to shut the valve, connect a funnel to the out flow hose of the raw water strainer, pour the acid into the funnel and use the a/c system pump to fill the system.
So I need to let it sit and percolate, or create a circular system with the strainer in the loop, using the system pump. It's going to heat up, though.