***a/c Confusion***

[ras_cal1]

I am struggling to figure out the A/C system on my '87 Bayliner 2850 Contessa Sunbridge. I bought it second hand and although I do have the original owner's manual, I have no hands on instruction from anyone on system operation.
Here's what is going on. I adjust the fan switch to the on position and the mode dial to cool with the cooling selection set at the "warmest" cooling position which I think is supposed to kick in the seawater pump to circulate water around the coils which is supposed to exit thru the hull outside of the compressor located under the dining seat. I traced the line and there are two that exit thru the hull from the A/C unit which I think one is for the water circulation and the other for condensate to escape? Anyway, even with the compressor set at the lowest setting, the fan switched to the on position, no water circulates and in about 30 seconds, the breaker trips.
So, I opened the engine compartment to verify that the seacock handle is in the open position which it was. Then I follow the water line from the valve another foot or so forward and the line is connected to an apparatus that resembles a fuel filter housing with a clear plastic cannister which is filled with water. Is this a water reservoir of some type to keep the pump primed?? Then the line goes another foot or so forward and connects to the pump.
when the compressor is running (before the breaker trips) the pump feels like it is vibrating to the touch but no clear sound that it is whirring/running/pumping and I don't know what it is supposed to sound like.
Does the compressor kick the breaker if the water is not circulating?
Would the pump not pump even if there is water in the plastic reservoir which would appear that the pump is primed because of water in the cannister to begin with? What am I assuming incorrectly here?
When the compressor is running for the short time it is, the fan does blow air somewhat cooler and as I increase the cooling adjustment towards the coldest setting, it kicks the breaker also.
Again, my gut instinct is that lack of water circulation causes the unit to self shut down.
Question, is the pump 110V or 12V?
And, ..one more question.....what is the apparatus under the floor (it has a floor access cover) that is located under the floor just in front of the area of the A/C control panel?? The water supply tube for the A/C runs right beside this apparatus which is somewhat rectangular in shape about 3" x 4". Does this work with the A/C system?
Sorry for all the questions but I am trying to be as descriptive as possible.
Thanks,
Boatman1

 

[This_lil_fishy]

Re: ***a/c Confusion***

The pump could be seized. An electric motor will vibrate a bit even if seized, heat up, and possibly pop a fuse or breaker. Our DC motors will do that when this happens. We've even seen a few catch fire because an on site 'technician' would bypass the thermal breaker on the motors. I am not familiar with those systems, so it's a shot in the dark.

 

[mlaymance]

Re: ***a/c Confusion***

I will do my best to help here. Typically the compressor on any A/C unit has a time delay built in the control circuitry. Until this timer expires the compressor will not start. You haven't said how long the system works before tripping the breaker. Compressor time delays typically run 3-5 minutes.

If the compressor operates on 115VAC It is pretty safe to assume that the pump that cools it operates also.

One of the 2 of these devices is causing the breaker to trip. I would start by isolating them. Disconnect one of them (tape up the wires) and try to run the system. If the unit operates more than a it has in the past, then the disconnected device is at fault.

If the compressor operates and stays running without tripping the breaker, the evaporator coil (the cool section of the system) should get cool within a minute. This should happen regardless of whether the coolant pump is working, although not for long.

Does the evaporator fan work? how cool is the cool air you are getting when you think it is getting cool.

In a marine A/C unit I would expect somewhere in the neighborhood of a 12-18 degree delta T (the ambient temperature near the evaporator coil minus the air outlet temperature (where the cool comes out).

A handy device that helps troubleshoot A/C systems is a clamp on amp meter. If you have one of these (or have an electrician friend you can borrow one from), many things can be checked. clamping it around the leads that feed power to the compressor, the coolant pump, and the evaporator fan will tell you which of these devices are causing the breaker to trip. DOn't discount the fact that the breaker itself could be bad either. If none of these devices show a high current state, then I would start by replacing the breaker.

If the Compressor is causing a high current trip, you may be looking at having to have it replaced. Same is true with the coolant pump, and the evaporator blower fan.

It would be interesting to know the brand/size of the A/C unit, and I may be of more help.

When you eliminate the good stuff.... all you have left is the bad.


Michael

 

[ras_cal1]

Re: ***a/c Confusion***

Thanks guys. I think I will start at the transom and work forward which means I pull and bench test the coolant pump first.

The compressor will run approx. 30 seconds and the pitch changes which I think indicates it has built pressure in the system? The fan runs and circulates air just fine. The breaker trips and when I reset it, the result is the same. 30 more seconds of running and it trips again.