Repair or replace marine A/C - Heat?

[cool beans]

Forward ac/heat in the master suite has a bad high pressure switch. It didn't cool or heat during any of my inspections or during the survey. Was reflected in the price, kind of hoped it would be an easy fix (popped fuse, limit switch, wiring, etc).

Turns out the high pressure switch is faulty. I currently have it bypassed and it is cooling now.

The high pressure switch has to be sweated off and on, it isn't something I can fix the unit has a history. It is a 20 year old domestic vcm12k run with the original 30 year old dial controls. The fan was replaced 10 years ago after shorting out and the compressor was replaced shortly after. The PO mentioned he had it "charged" but I have no receipt. It's an r22 refrigerant unit.

I need to get a quote to fix, but if anyone with experience can give me rough estimate I'd appreciate it. Also, when is something like this throwing good money after bad? Not that I'd be happy to spend it, a new webasto unit is $1500 and should drop in.

Thanks! Experience and insight are appreciated!

 

[ddalme]

I feel your pain. Did the exact same thing two years ago. My old unit (20 plus) spent $600 to repair and it worked marginally. Ended up replacing for about 2K with new controls. Don't try to fix it-you'll still have a 20 year old fixed unit. Just my thoughts.

 

[O C Diver]

I pulled all 3 of my 13 year old units out and replaced them with new when I did my refit. The unit you have is likely a piston compressor, now they use rotary which are much more energy efficient. IMO, they are little more than a water cooled window shaker (window air conditioner). The lower amp draw is easier on the generator and I don't have to worry about it failings while I'm cruising. A 15 year old air conditioner owes you nothing, time to upgrade.

Ted

 

[The Other Gary]

And the new ones also have the split capacitor fan motors instead of the old shaded pole motors. Overall they are much more efficient and quieter. And no more rusty condensate pans as they are all plastic or SS.

 

[Dani-lu]

I concur, time to buy a new AC. The new ones are quieter, more efficient and in my case has a stronger fan.

 

[FF]

"I concur, time to buy a new AC. The new ones are quieter, more efficient and in my case has a stronger fan."

The question then is how much heat will be required and do you pay for your electric?

The new Mini split units are not "marine" and need no water supply.

They are quiet more efficient and easy to zone .

Best , for a liveaboard is 300% to 500% more efficient when heat is required.

 

[sdowney717]

Forward ac/heat in the master suite has a bad high pressure switch. It didn't cool or heat during any of my inspections or during the survey. Was reflected in the price, kind of hoped it would be an easy fix (popped fuse, limit switch, wiring, etc).

Turns out the high pressure switch is faulty. I currently have it bypassed and it is cooling now.

The high pressure switch has to be sweated off and on, it isn't something I can fix the unit has a history. It is a 20 year old domestic vcm12k run with the original 30 year old dial controls. The fan was replaced 10 years ago after shorting out and the compressor was replaced shortly after. The PO mentioned he had it "charged" but I have no receipt. It's an r22 refrigerant unit.

I need to get a quote to fix, but if anyone with experience can give me rough estimate I'd appreciate it. Also, when is something like this throwing good money after bad? Not that I'd be happy to spend it, a new webasto unit is $1500 and should drop in.

Thanks! Experience and insight are appreciated!

Ok, the high pressure switch shuts off the compressor if the refrigerant pressure gets too high like over 400 lbs maybe.
That can happen if the cooling water flow stops.

However, this is done to save the compressor from breaking its piston, or overheating the windings which will short out and pop open the breaker.
Another thing, a high pressure overload of the compressor will cause it draw more current and will eventually also pop the breaker shutting it down. The high pressure switch is just there to act quickly to save the compressor.


Another thing you could do , is drop the circuit breaker from 20 to 15 amps, which would make the circuit breaker more sensitive to compressor overloading.
All breakers can run overloaded a little before popping, but they are rated to run at their rated value. My breaker is 20 amps, but the unit never draws more than 12 or 13 amps, unless the water flow shuts down or it won't start due to a faulty capacitor.


I would just use it like you have it, it is cooling, it could work fine for years as is. When it breaks then replace it. Unless you are impatient.

 

[TJM]

"I concur, time to buy a new AC. The new ones are quieter, more efficient and in my case has a stronger fan."

The question then is how much heat will be required and do you pay for your electric?
The new Mini split units are not "marine" and need no water supply.
They are quiet more efficient and easy to zone .
Best , for a liveaboard is 300% to 500% more efficient when heat is required.

FF: Which split units are you referring to ? I have a 1982 President and need two units replaced, I am a yr round liveaboard in Ct.
I think you are referring to the units that have a water supply / compressor in the engine room and then a blower and controls where needed, correct ?

 

[cool beans]

Ah, the wisdom of aged and learned mariners

I'm going to leave it jumped for now, and shop the up coming 4th of July sales for a new Webasto unit. On top of the high pressure switch, I've been watching it ice up to a certain point in the coils....

Not in a rush, but I'd rather not run a wonky unit into the hottest part of summer

Thanks everyone!

 

[hmason]

Yes, replace it. We went through the same exercise in FL. Spent too much fixing the damned thing and then replaced anyway. Our new units just "loaf along" to keep us cool where the old ones struggled. Don't throw away your money on repairing the old stuff as something else will go wrong soon after you fix the first problem. Believe me I know.

 

[LarryM]

Ah, the wisdom of aged and learned mariners

I'm going to leave it jumped for now, and shop the up coming 4th of July sales for a new Webasto unit. On top of the high pressure switch, I've been watching it ice up to a certain point in the coils....

Not in a rush, but I'd rather not run a wonky unit into the hottest part of summer

Thanks everyone!

I was looking at Webasto to replace an aging Marine Airrr unit until I read in their literature that their units are manufactured without service ports. There is no convenient way to check pressures or add refrigerant. You might want to check with your local AC service providers to determine what impact this might have on future serviceability.

I found that for about the same money, I can get a Dometic ECD Series which is very 'conventional' in its layout and uses commonly available components and controls.

 

[kev_rm]

"I concur, time to buy a new AC. The new ones are quieter, more efficient and in my case has a stronger fan."

The question then is how much heat will be required and do you pay for your electric?

The new Mini split units are not "marine" and need no water supply.

They are quiet more efficient and easy to zone .

Best , for a liveaboard is 300% to 500% more efficient when heat is required.

500% more efficient than what? A kerosene lamp? I struggle to understand a water cooled marine heat pump is 5 times less efficient than a poor man's split.

 

[FF]

Which split units are you referring to ?

There are many brands , the hard part seems to be to find a 120V unit as most are 240V .

120v is still more common at marinas.

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" 500% more efficient than what"

When the outside air temp or water temp gets to about 40F the ancient units stop working as the medium they are removing heat from freezes.

So at about 40F they will switch to a toaster wire.

A heat strip that is "100%" efficient , but makes damn little heat for the huge electric cost.

The modern mini split will be 3x to 5x as efficient at making heat , even down well into below zero F .

Folks still fear high energy costs , so there is no going back , in a few years I think the water cooled air cond will be as antique as a water cooled stuffing box.

 

[SeaMoose]

I have two Daiken mini splits in my old house, and sure, they work well but where would one put the compressor that's on the outside of the house? Certainly not in the ER, without huge fans to vent the waste heat. On the fly bridge? Maybe on a large vessel.

 

[clynn]

Not to hijack the thread, but I'm in a similar "boat" with a couple of old cruiseair a/c units. Both are chillers, two compressors three air handlers. For those of you that have replaced these units, are they simply drop in, as in a handy owner can replace them? Do you use the same wiring and and just replace the units and controls? I would LOVE to not have those old dial knobs that basically just turn it off or on.

 

[O C Diver]

Not to hijack the thread, but I'm in a similar "boat" with a couple of old cruiseair a/c units. Both are chillers, two compressors three air handlers. For those of you that have replaced these units, are they simply drop in, as in a handy owner can replace them? Do you use the same wiring and and just replace the units and controls? I would LOVE to not have those old dial knobs that basically just turn it off or on.

While you can likely use the raw water system, ductwork, and electrical circuits, everything else is probably different. For most all in one marine units, the foot print has gotten smaller and they're very plug and play setups.

Ted