Airr marine HVAC problems. Ideas Please

Hello,

My first post on the forum but have been reading & learning over the last few weeks. Awesome stuff in every thread.

I hoping to solicit ideas or comments about our vintage Air marine system.

Our new to us boat has 3 cooling/heating units 16,000 BTU each. One unit works fine, one unit worked fine during the haul-out survey.. but the broker turned it back ON with an airlock in the system and it has not worked since… Another broker came in and showed us how to bleed the system before we turned on the other 2 units. This unit’s fan runs fine, thermostat clicks as expected but no heat or cold. Husband checked capacitors and they seem fine. So we are stumped on that unit. Possibly it needs refilling.

Third unit worked fine for a few weeks but its fan suddenly stopped. Condenser comes on fine.. capacitors are fine. Husband swapped a working fan controller from one of the other units to this unit but still no fan. But when connecting the fan wires from this unit to another working unit (that is in the off position), the fan in the other unit runs fine. So we think the fan motor may be the problem, despite the fact that the fan turns freely by hand.

Sorry for the long post..I have been trying to schedule a tech to check the units… everyone is swamped… call back in November I am told. Seriously!

Thank you for comments and ideas

Raylee

Assuming when you say airlock in system you are referring to the cooling water loop? If this is the case the high pressure cutout may have a manual reset (red button on the sensor) that has been tripped and needs to be reset.
Easiest way to check a fan is to disconnect the harness and power it directly to see if it runs. They can still spin with a dead motor. Also there are direct replacement fractional hp motors available for reasonable cost nothing marine special about it.
Hope this gets you started.

Welcome aboard.

Thank you for the comments. Back to the boat tomorrow and will certainly try the reset aspect. ��.
Thank you

+1 on the fan, and the hp sensor. Also verify you have water flow and discharging for the water loop. Check your strainers, throw in some brominating tablets in the strainer for good measure.
While a/c's are simple, they have many complex things hapening at once. To properly diagnose, get a set of guages on it... you can likely find another guy on your dock with the equipment and knowledge to help troubleshoot further. I suggest paying attention, these are valuable skills given ac never quits at a good time

First: Welcome to the Forum!

Now on to your concerns . . .

You used the word "vintage" in your post. Exactly how old are the AC units? If they are original equipment, you may want to consider replacing them all. That is what we are in the process of doing. While you are at it, I would recommend replacing the raw water cooling hoses as well. Better to start off fresh with all new. Expensive, yes, but you will be starting off with known units, and will probably last you for as long as you own your boat! New units tend to be more efficient, and draw less power as well.

You need 1 GPM per 4000's BTU's, So one unit will need 4GPM. 3 16,000 BTU's unit's will need at least 12 GPM of water to run. Add in all filters/strainers, 10 feet of hose, a few 90 degree fittings/bends and your pump should be pushing 20 GPM. I've got the same setup(3 16,000 BTU's) and Dometic says I need a 30 PGM pump, and they are right, as my 12 GPM pump would not keep the high pressure from coming on.

Also, disconnect and reconnect all the electrical connections. I have to do that a few times a year. I'm based in Corpus Christi, Texas where the water temp is 88-90 degrees and High pressure is a constant problem. I run AC year round.

The Brockerts

Thank you very much for all the comments. It seems that our units have an automatic reset, so unfortunately no red button to reset.

We have full water going through the system, strainer is clean.. We will check on the pump’s gpm capacity. We may need to upgrade it. The units are the blue colored which I am told that are from the early ‘90s. This boat spent all its time in either San Fran or Seattle. So the units were hardly used, they look pretty good.. no rust, nothing in the pan, the hoses look newish. They are self-contained units in the living areas.. nothing in the engine room except the water pump.

I finally managed to get a tech for a couple of hours to look at things. First, he mentioned that parts for these units are not easy to find. He usually takes parts from one unit to fix other units. He found that all 3 units have plenty of refrigerant. Since this is the old refrigerant, he usually takes refrigerant from one unit to top off other units. If need be. But we are good on that front.

As we expected, one unit has a defective fan motor and the other unit has a stuck/defective reversing valve. He recommended taking replacing the fan motor from the other defective unit.

To fix the reversing valve, we are told that he would need to do it in his shop on a bench and labor cost would be significant enough that he recommended to install a new unit.

My husband did the fan motor exchange and that fixed the issue with one unit. We will try to find an outfit that can possibly fix the fan motor. With the fan motor out, the reversing valve is easy to reach. So I am not sure if the fix can be done in situ. I suspect that the tech may need to pull out all the refrigerant prior to exchanging the valve.

In the meantime, I am researching new cooling units that would fit our needs. Since we purchased the boat, we only had a need to use the AC on 3 occasions for sleep. But we still need to get the last unit operational.

Thank you again for the insightful comments and help.

Raylee

Replacing the reversing valve requires evacuating the freon, and putting it back when done. I'm guessing that the repair will be pricey. Btw, the valve is soldered to the plumbing connections. My preference would be to have it done off the boat. If it were me, I'd replace the unit. If you plan to use AC on the boat, I would want something reliable, not wondering when the next component will fail.

Ted

Put me in the column with Ted. Any unit that uses R22 isn't a candidate for any repair that requires any refrigerant work, the expense just can't be justified. You'll spend premium dollars to repair a system that's beyond its service life, and no assurance that it won't fail the day after the repairs are completed! As Ted replied, a reversing valve replacement should be done on the bench, so you're duplicating the labor that would be required to replace the entire unit, notwithstanding the actual repair. So it's a no-brainer. A new unit would be quieter, more efficient, repairable, warranted, and wouldn't be waiting for the other shoe to drop!

Give that reversing valve a few taps with a hard screwdriver handle while commanding hot and then a minute later commanding cold and back and forth. Many times they can be unstuck.

Thank you all for the comments and ideas. As an update, After failing to unstuck the reversing valve, we found 2 self-contained brands that fit the space. One Wabasto and one dometic. Right now we are trying to figure out how to tie either one to the marineair control box. Both come with their own controller so we need to tie them to the only have one water pump on board, which is currently tied-in to the other 2 original working units.

I would appreciate learning from anyone who has done such a thing before or has insight of the logistics.

Thank you much

If multiple units are sharing a water pump, there should be a relay box that turns the pump on whenever any of the units powers its water pump output. If that's the case, then you can connect the wires that are currently connected to the pump output of the old unit to the pump terminals on the new unit and that should still drive the relays and work as expected.

Make sure raw water strainer is sized correctly. Mine was not and when the water heated up this summer it revealed its incapacity to flow enough water. Upgrading tomorrow to the Groco 750 for a 48k BTU.

If you can’t get the relay box to play together you can wire the pump to it’s own breaker and just turn the breaker on before you turn the A/C on. Down side it the pump will run continuously.

Why do you want to go to a single SW pump?

What's the BTU rating of each units and the GPH of the single SW pump?
I have a 12K and a 16K A/C unit on a single SW pump. Each A/C has a breaker and breaker for the SW pump.
The SW pump is a Little Giant is rated at 1800 GPH. My tech recommended a 2000 GPH SW pump.
Each unit has it own start relay and a soft start.
The SW pump has it own relay.
The tech installed siilicon based hoses,
The SW strainer must be 1 inch in and if I heard him correctly, the rest of the SW system 1/2 inch.
Basically, the SW pumps runs when either or both A/C plants are running.

Now you know as much as I do.

I think I will let him let him do the recommendation.

Thank you rslifkin, Osprey69, Commodave and OldDan1943.. great & thoughtful info. We only have one SW pump supplying 3 x 16K older marineair self-contained units. Thats the original design. I am thinking of replacing one of the older nonfunctioning 16K units with a Dometic 10K Enviro unit, or a 16K Wabasto unit. Both will fit the space. If we go with the 10K unit, I was thinking it would go in the master cabin as its size is contained with doors closed.

Ocean water on the west coast is usually on cooler side, especially where we end up cruising in the PNW or BC.
We have not been able to ascertain the GPH of the pump but still researching it. When the tech was here 3 weeks ago, he looked at the pump in the ER and did not make a comment either way. I understand that we need to get an accurate GPH.. we may still need to upgrade the pump. Thats a relatively straight forward task, I think.

Thanks much

Is anything ever a straight forward fix???

Raylee said:

Thank you all for the comments and ideas. As an update, After failing to unstuck the reversing valve, we found 2 self-contained brands that fit the space. One Wabasto and one dometic. Right now we are trying to figure out how to tie either one to the marineair control box. Both come with their own controller so we need to tie them to the only have one water pump on board, which is currently tied-in to the other 2 original working units.

Click to expand...

Raylee said:

Thank you rslifkin, Osprey69, Commodave and OldDan1943.. great & thoughtful info. We only have one SW pump supplying 3 x 16K older marineair self-contained units. Thats the original design. I am thinking of replacing one of the older nonfunctioning 16K units with a Dometic 10K Enviro unit, or a 16K Wabasto unit. Both will fit the space. If we go with the 10K unit, I was thinking it would go in the master cabin as its size is contained with doors closed.

Click to expand...

If your original units were Marine Airrr Vector Compact models, the most direct replacement now is the Dometic DTG. (This after Marine Airrr introduced their Vector Turbo model, Dometic acquired Maine Airrr...)

There are versions that will connect to the original Marine Airrr wall panels, and I suspect this includes the Passport IO panels as well as the later Elite panels. My experience with this replacement on our previous boat was decent; the new DTGs are quieter, move more air, the drain pan is composite so no rust, same footprint as predecessors, etc. Sometimes you can get a ~20% "boat show discount", depending...

(Ditto same experience replacing a Cruisair StowAway model on this current boat.)

There's also a CTM unit, said to be another direct replacement, and which is said to use with several different control panels. Less expensive, decent features on paper...

-Chris