Another A/C problem

JimmyDubai

JimmyDubai

Member
Oct 13, 2015
351
Dubai, UAE
Boat Info
Sundancer 290 1996, one big block Mercruiser 7.4 LT
Simrad Go9 XSE + 3G radar
Engines
One, Mercruiser 7.4 V8, 310 HP
Guys, my A/C can't cope with the heat.

Temp outside is between 95 to 102, so to be realistic I set the controller at the max temp which is 85. Once the A/C is on, the temp starts coming down but it would take 15 min to shut off and die (from the breaker box). I then need to wait a while until I'm again able to switch it on.

I can see other boats at the marina and all have the A/C operating continuously, mine can't.

Where shall I start from?

Thanks
 
Start at the thru hull, if I remember you had a bottom fouling problem recently. If the intake scoop has growth in it, it will restrict water flow and cause the unit to cycle off on high head pressure. Next, be sure the sea strainer is clean, they can fill up with growth, crud etc and also restrict flow. You may want to run some acidic cleaner through the coils to clean out the gunk and buildup that forms inside the cooling coils of the unit. There are several threads recently on doing that. I've used Lime Away with good results, others have used Barnacle Buster etc. Do a quick search for more details. Also, you may want to have a tech check the freon level in the unit to be sure you have a full charge since you are in extreme conditions.
BTW what is the ambient water temp there? The warmer it is, the lower the efficiency of the unit will be. You may have too small of an AC for the high ambient air/water temps.
 
Yes Scorpio, I had the hull recently cleaned out and I made sure the suction of the A/C water pump was left clean. I can actually see a good flow when the pump is on. I will try to get a product to clean the piping as you said. Water temp is high as you would imagine, but again I can see other boats having A/C working full time. I was thinking about an electrical protection system for the A/C motor that could be set too high (meaning it should go off not too soon?).
 
I'd have a tech check the freon level in the unit, it may be low.
Has this unit ever acted like this before or is this something new?
 
Until two weeks ago the setting was from 85 low and 88 high so it would work between this range with no issues. Now that outside temp is significantly higher, it can't stay for a long period of time. I'm sure if it stayed on longer, temp would come down to the mid 80's.
 
One of the benefits of a water to air heat pump is that the water temperature for the "outdoor coil" does not vary as much as it would with an air coil. The temperature of the water certainly will still affect the load on the compressor but I doubt you have seen that dramatic of a water temp change in the last couple of weeks. The ambient air temperature affects these units much less than it would a typical air conditioner. Extreme cabin temp could cause the high amp draw just like extreme water temp but standard design ambient is 95 Deg. F. so its not that far out of design even at 102 degree cabin temp. Enough to prevent it from cooling to 72 degree cabin; not enough to trip a breaker on high amp draw. A clogged air filter or "low load" condition on the indoor coil will actually create a decreased amp draw condition. It could cause a freeze stat to shut down the unit but that would not also trip a separate breaker. Too much refrigerant will cause high ampdraw (unlikely) and too little refrigerant will slightly reduce ampdraw but will reduce cooling both internally and externally. This could cause the compressor to overheat and result in high ampdraw. The condition of the compressor and the state of related electrical connections would be my guess. A compressor that is failing due to age or intense overheating would do exactly what you describe. Equally as likely (and much less expensive) would be a poor electrical connection on an inductive load, compressor, fan, pump etc. The likelihood of high ampdraw due to a corroded electrical connection on a boat is quite high. Check connections for discoloration or corrosion with the power off. Cleaning and reconnecting something like a compressor motor connection could make the difference.

Sorry for such a long response.


Sent from my iPhone using Tapatalk
 
Not at all! Well explained, thanks

That will be my weekend, checking out all potential causes

How clean is the air filter in front of the evaporator? It is clean Mike, I replaced it 3 months ago.
 
Alright, so I went to the marina today and I found two things:

- the breaker of the power station at the berth of my boat had gone off

- Once the power was reestablished, after 10 minutes of operation the fan electric motor gets pretty hot, and after 20 minutes the systems shuts down (breaker at the boat panel goes off).


Motor below

4767915_20140723114822858_1_LARGE 1.jpg

IMG_2232.jpg

So questions.... is it normal that the temp of that motor gets really hot?. What part of the white box (electric stuff) should I check to see it this is indeed the culprit?
 
Sounds like the blower motor bearings are gong bad and causing the motor to heat and blow the breaker. The motor will get warm normally but not hot. Put a IR thermometer on it and see how warm it's getting. Sounds like a new one may be in order.
 
Folks,

In parallel to trying to find the electric motor issue, I also would like to flush the piping. I remember to have seen a thread about this; do you know how to properly do this? materials, procedure, etc. I could easily ask a tech but they will charge loads of money and I want to learn and do it myself.

Thanks
 
SCORPIO said:
Sounds like the blower motor bearings are gong bad and causing the motor to heat and blow the breaker. The motor will get warm normally but not hot. Put a IR thermometer on it and see how warm it's getting. Sounds like a new one may be in order.
Click to expand...

I removed the motor, sent it for check up and it is good!! 2.7 AMPS running and it gets a bit hot but they said it is normal, so now I will have to find the solution somewhere else....

The problem to me is electrical; what if I start the A/C without the motor (blower) for a few minutes just to make sure the motor is excluded in the electrical circuit?.
 
OK, I went to the boat today and tried to get the system started unsuccessfully, the panel shows three digits (888) and it dies after a few seconds meaning that the shortcut is somewhere else; I didn't want to go Plan B but I will have to ( call the technician).

It is horribly hot inside the cave.....
 
I just noticed your location. What voltage are you getting? I assume you are getting 120 V because you would be experiencing other problems but low voltage will cause high amperage.

Either way I agree with electricaldoctor, you have done the right thing checking the amp draw on the indoor fan and now should check the amp draw on he compressor.


Sent from my iPad using Tapatalk
 
Power in Dubai comes as 220 V but I have a transformer down to 120 V. The A/C worked well all winter and spring and precisely now that we are in a hot hot summer, it decided to make me sweat....
 
JimmyDubai said:
Power in Dubai comes as 220 V but I have a transformer down to 120 V. The A/C worked well all winter and spring and precisely now that we are in a hot hot summer, it decided to make me sweat....
Click to expand...


Are you getting 120 VAC from the step down transformer? If that is going bad and you are only getting say 98 VAC would that cause the problem? I don't know. I once had AC problems at a marina that could not provide 120 VAC clean and steady. Just a thought. Any electricians out there?
 
LOL, yeah, I know!! The technician is coming on Sunday
 
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