-A/C issue, 1987 Carver 4207 Please help

[steve&tammy]

Hello all
Ok, so our new to us 1987 4207 has been a blessing of many fine things since we've taken possession this past winter. She's so close to her old self and we're enjoying all that we've accomplished with her along the way.
However, the AC system has been a tough nut to figure out. Yes, I did some searches throughout our wonderful forum and failed to find my current issue so please bare with me...

Original units front, salon and rear. Yes, they're old but when they're running, they run fine. Put out great, cool air. Fans work fine, seriously very surprising but yes, once up and running, they're fine.
They all slave off of the forward stateroom (from what I can tell) meaning that when you turn that one to start, it does indeed start the water pump.
A couple months back though, the whole thing was acting up meaning I would start from forward to back and yes, it's all pulling about 44 amps at the interior salon breaker so I know that's a bit high, but again, it's mostly from just being old. Anyway, it would run, they it would pop the main breaker on the salon panel. (not the other 4 sub breakers)
I'd wait a bit, start it up again, then it would run and then like 15 minutes later, it'd pop main again. Then I'd start with just the front. Here's the deal, I'd have the front going for literally 45 seconds and it would then stop.
I found out that the water pump was getting hot and barely running...like I pulled up the galley cover over it and could see that it was barely moving and smelled like it was burning up.
So, I replaced that there pump with a brand new (1000GPH) one and sure enough, it would do the same dang thing.

Therefore, I'm down to these potential issues???
1) I believe that once the ac units are up and running, they're fine. But, they may be too close to the limits of the 50 amp salon breaker so I should change that, correct?
2) Once that's done, is there a relay going from the front ac unit that tells the water pump to go on? If so, where? If so, do those go out? I'm assuming that what's been happening is that the front ac is saying "Hey water pump, go" And then the water pump is like "Hey, I'm brand new...BUT, I'm not getting the correct 'signal' so I'm going to stop and tell the front ac unit to turn off as well.
What else might it be?
Please help, it's hot and only getting hotter in these dog days of summer!

[waybomb]

Did you take the cover off the strainer to make sure the in hull pick up isn't clogged or the strainer basket full of stuff?

[km1125]

You may need to do a flush on all the condensors for the units so that there's no resistance to the water flow. If the main water pump can't flow a lot of water, it can't cool itself down either. If there's not enough flow of water, each unit will draw more Amps than normal even though it might be providing adequate cooling. If it gets bad enough, at some point either they will trip a high pressure sensor or a breaker will trip.

Usually where you have multiple systems there's a relay system so any one unit can activate the pump. That may have been bypassed by a former owner and then just wired to the forward unit. You may have to do some digging on that. I would follow the power wire from the water pump and see where it goes.

You should look for the info labels on each unit, so you know exact models you're dealing with. I'm guessing you have a 16kBTU, a 12kBTU and an 8kBTU (which would be typical for that style of boat) and with those three operating your total current draw should/would be closer to 30A.

[Midnightsun]

As mentioned the pump gets activated by any unit when turned on and circulates water through all 3 even if they are not running. Drawing 44a on a single 50a breaker is pushing it so this may be your issue especially if there is something else on the circuit. I do know my factory setup has 2 units on one 50a circuit and the other on another 50a circuit.

Do not change the 50a breaker as the wiring is not designed for a larger draw. Best solution would be to move one of the units power source to your other 50a breaker.

[buster53]

Quick question…
You replaced the water pump….is the discharge a good, strong stream that looks like it might be pumping near the 1000 gph it is supposed to be pumping? If not, you could have a gunked up strainer, unwanted growth going on in the hoses, partially blocked intake, etc. Do whatever is necessary to get the pump pumping as it should be and then, maybe reroute one of the AC units to a different breaker. I would suggest rerouting the smallest of the 3.