a/c breaker keeps tripping

[Squanderbucks]

My experience tells me your issue is probably one of three things. Circulating pump is faulty. ( my last one did the same). Ran for 20 minutes and quit. Causing unit to overheat sad shut down or trip breaker. Secondly a faulty high pressure switch. Or low “Freon”.

If your pump is loosing prime then you have an air leak before the pump. It will not self re prime.

[Turtle Blues]

Measure a couple of things to guide you.
What is the amp draw when the pump is running compared to its rating? and when does the breaker trip?
This will tell you if it is a faulty breaker or the pump current draw.
If the pump are you sure the intake and strainer are capable of full volume delivery to the pump?
What is the temperature differential and volume of water going through the cooling exchanger coil? Is it in need of a chemical flush? Partial obstruction or restriction causes high head pressure which will over heat the pump and cause high current draw.
Sorry not an answer, just what you need to get there.

[sneuman]

Now it seems to be running without tripping. Water flow is good. But it doesn't seem the fan is working -- no cool air.

[Turtle Blues]

No cold air, or no air at all?

[sneuman]

Originally Posted by Turtle Blues

No cold air, or no air at all?

No air at all, actually.

[Turtle Blues]

So the original setup for this unit would have had the water pump wiring coming off the control board and the entire system on a single breaker. If the water pump as you said is now on its own breaker is there a second breaker - possibly tripped - for the rest of the system?

[sneuman]

Originally Posted by Turtle Blues

So the original setup for this unit would have had the water pump wiring coming off the control board and the entire system on a single breaker. If the water pump as you said is now on its own breaker is there a second breaker - possibly tripped - for the rest of the system?

There's only one breaker on the main panel that I know of. I assume there's another in the unit. But it's all ensconced behind a panel now. If it's simple, I'd rather not tear all that out.

[pesarsten]

Some basics
circulator pump draws little current, since it runs for a while, ( Compressor start delay?)
Its possible , ( likely) that the breaker trips when the compressor tries to start. Low flow will cause high current and possible trip but ONLY after the compressor has been running for a minute or two in almost all cases. The problem can be in several areas , not all causes are hard to fix or diagnose. Could be bad breaker, wiring, start cap, compressor, blower..... Diagnostics are key to not wasting time or money.
First you must measure the Load current when the breaker trips. Easy to do with an inexpensive clamp on a/c amp meter.
If this is not within your comfort range get some pro help.
PM me if you want my phone number, I spent many years as a licensed HVAC tech.

[Turtle Blues]

The boards for these units usually have only relays for controlling the pump, fan and compressor. if there is a fuse it is control protection. the exception was if you have multiple units on a common pump. then there is a second external box for the pump controller.
Unfortunately you are probably going to have to access the board for some diagnostics. Next step is really determined by you.
Don't know your comfort level with opening the box and using a voltage tester / multimeter? If not probably time to call a marine ac tech. Port Directory has listings by location, plenty on the bay.

[Boatwright]

"Don't know your comfort level with opening the box and using a voltage tester / multimeter? If not probably time to call a marine ac tech. Port Directory has listings by location, plenty on the bay."

A number of things have already been mentioned:

Compressor pistons stuck from a long period of no use. Problems with control relays. Bad wiring. Etc., etc., etc..

You express reluctance to get into the guts of the wiring and control box, and haven't yet measured amperage, etc.. I second the suggestion that rather than jumping around looking for a "simple" fix for a problem with many possible causes it's time to call a qualified AC tech.

[sneuman]

It was more a question of some artificial urgency, as I am pulling the boat out of the water this week and will be harder to mess with the a/c on the hard (although, I suppose I could just attach a hose to the thruhull. It's not a critical system, and I can try to sort it when I get back in the water next spring.

Thanks for all the advice. It gives me a starting place when I go back at it!

[dauvillier]

Originally Posted by sneuman

I have a Marine Air Systems A/C aboard an older boat that is new to me. Experimenting with it, I find that I can get the pump primed and it will pump fine for about 10 minutes or so, after which time it trips the breaker and shuts off.

Any ideas on what might be going on? Thanks in advance.

Check the water pump, not cooling enough. Or not at all cooling.

[garychurch]

If it runs for 10 minutes it sounds like it’s overheating. One cause could be build up of barnacles and growth in the coils. A good flush with barnacle buster May solve your problem.

Another problem could be your pump overheating do to failing bearings. Using an infrared temp gauge on the ends of the motor may verify a problem. Assume you do not hear bearing failure noises.

Good luck.

[Dieseldude]

Originally Posted by sneuman

I have a Marine Air Systems A/C aboard an older boat that is new to me. Experimenting with it, I find that I can get the pump primed and it will pump fine for about 10 minutes or so, after which time it trips the breaker and shuts off.

Any ideas on what might be going on? Thanks in advance.

You need to determine if you have an electrical or mechanical problem. Check for any obstruction in pipe work and strainer. Obstructions in either the suction or discharge could overload the motor. Is there any hose in the system that could be pinched or collapsed? When last were was the condenser cleaned? The tubes could be obstructed. For your safety, isolate electrical power before putting your hands near the pump while checking it. Are there any grease fittings on your pump? If so give them a couple shots of a good bearing grease and see if this helps.


Get access to the shaft and try turning it by hand. It should spin freely. If you feel any unusually stiff resistance, there could be foreign material against the impeller, or the bearings could be bad. Rotation should be smooth and steady. If the bearings feel "gritty", they are bad. Check for bearing side play. If you can feel side play, the bearings are probably worn. Normal side play should not be perceptible to the hand. For precise testing, you would need a dial indicator to measure side play and check this against manufacture's spec's. If side play is bad, you would probably hear and feel strong vibrations. If bearings are suspect, find out if it is motor or pump bearings by uncoupling the motor and spinning pump and motor independently.



Assuming that this is an AC powered system, not DC. An AC clamp amp meter will give you the ability to monitor the current draw as the pump runs. Check the motor data plate for maximum amps spec. to know what is allowable. If your system is DC powered, DC clamp meters can be had, but they cost more. If you have no clamp meter, you might try temporarily changing the wiring to run the pump off another breaker. A cheap clamp meter will do the job, and might be had for less then $100. Perhaps the breaker is bad, and tripping at lower than its rating.



If you run the motor while it is uncoupled from the pump, and the breaker trips, you will know that you have a motor problem. If you have a meg ohm meter, the motor windings can be checked for a partial short. There is a proper procedure and spec. for this that must be known, otherwise take the motor to an electric motor shop and ask for an "insulation test" or "megger test".


These basics should reveal where the problem is.

[Mauruuru]

My pump is driven from the A/C breaker and is controlled by the A/C controller. I had a problem with my compressor and the temperature limit switch would trip and then the system shut down. Of course the water pump would turn off too. Is the pump magnetically coupled impeller? If not is it leaking along the shaft onto the motor housing? If so time for a replacement with a magnetically coupled impeller (totally sealed pump).
Are there other things going on like high temp/low pressure switches shutting down the system? A typicall AC circuit breaker will carry 1.5 times rated current forever, and 2X for hours to days before tripping on overload. Because the time/current characteristics are logarithmic it will take a real motor/pump problem to trip the breaker on load alone.