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Old 07-19-2014
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Electrical help please

Hi,

I have a problem I like to get your advice on. I have a 1978 Pearson 323 with air-conditioning. The air-conditioning unit was installed by the previous owner, so I have no idea how old the unit is. It is a standard 120 V system which runs only on shore power. The air conditioner will run for about 10 minutes and then the circuit breaker will turn off. If I wait for a minute or two and reset the breaker, the unit will run for a much shorter period of time before the breaker turns off again.

Because of the location of the shore power I have no choice but to run two standard 30 amp power cords connected in series. I thought that the breaker might be weak because of its age, so I replaced it with a new 20 amp breaker identical originally installed. Unfortunately this did not solve the problem. When the compressor turns on the amp meter momentarily kicks up to between 15 to 18 A but then drops down to the normal draw of approximately 10 – 11 A. The onboard voltmeter shows an input of 120 V. My next step is to replace the onboard receptacle, although there are no obvious signs of corrosion or burning. But before I proceed I would like to get your thoughts on correcting this problem.

Thanks in advance.
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Old 07-19-2014
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Re: Electrical help please

Try a 30 amp breaker in the shore power line but only if you have boat side breaker protection on the branch line that feeds the ac unit sounds to me like you have a high loss due to length of shore power cables however don't leave unattended during the power test and check everything three times JM 2¢ worth
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Old 07-19-2014
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Re: Electrical help please

An old (20-25 year old?) air conditioner probably has lost Freon. This results in the compressor running overtime and drawing too much current trying to compress "air" in the system instead of Freon. If the air conditioner doesn't have an internal breaker, the overload may throw your line breaker. They can do that (overload) for other reasons as well.

I'd suggest putting an ammeter in the circuit (a clamp meter or anything that can read 20-40 amps such as one of the "Kill-a-watt" AC gizmos) to see just how much power the air conditioner is drawing. If it is over the rated power, look to replacing it, as servicing them is usually more expensive and less reliable than replacing.
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Old 07-19-2014
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Re: Electrical help please

I am not sure what a "standard 120v" air conditioner is. If it is water cooled, or supposed to be, do you have good water flow? Is the circulation pump running? Strainer clogged? Seacock closed? If it's an air cooled unit is it hard wired into your boat or run off of a cord? If it is run off a cord does the cord get warm near the receptacle it's plugged into? Does the unit put out cold air before it trips a breaker? What is the manufacturer? More info would help troubleshooting via the internet.
As HelloS said above, unless it is something very simple, it will probably make more sense to replace the unit with something newer and more efficient.
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Re: Electrical help please

Generally when motors and stuff get old it takes more energy to turn worn parts,. This shows up as internal heat and causes things like fuses or built in thermo safety switches tell you they're not happy. Piss them off enough and they burst into flames of displeasure.
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Last edited by Capt Len; 07-19-2014 at 06:48 PM.
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Old 07-19-2014
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Re: Electrical help please

To clarify: 120v-not 240v. Water cooled, reverse cycle (heats as well as cools) yes, good water flow. Circulation pump is running. Strainer does not seem to be clogged as water flow is good ditto for the seacock not being closed. Unit puts out cold air before the breaker trips. Could the air conditioner draw more amps by itself than the 10 amps indicated on the onboard volt meter? I don't know off hand what the unit is suppose to draw, but I will check the next time I am at the boat.Yes, the power cord does get warm at the boat receptacle, which is why I was wondering if that is where the problem is.

Thanks for your interest.
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Re: Electrical help please

Which breaker is tripping the main AC breaker for the whole AC panel or the branch breaker for the air conditioner circuit?
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Re: Electrical help please

"To clarify: 120v-not 240v. Water cooled, "
Oh, then it is not a "standard" air conditioner at all. Like you buy for $99 in the ads in the Sunday paper and then stick on a boat.
It's a standard water-cooled marine air conditioner.

And the water cooling system is the first thing to suspect. Check th eflow and if there's any doubt about it, try using a garden hose and cooling it "for sure" to see if it keeps running. Old water cooling or pumps are likely to be problems.
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Re: Electrical help please

Check for jelly fish .
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Old 07-20-2014
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Re: Electrical help please

Quote:
Originally Posted by Boomer14 View Post
Hi,

I have a problem I like to get your advice on. I have a 1978 Pearson 323 with air-conditioning. The air-conditioning unit was installed by the previous owner, so I have no idea how old the unit is. It is a standard 120 V system which runs only on shore power. The air conditioner will run for about 10 minutes and then the circuit breaker will turn off. If I wait for a minute or two and reset the breaker, the unit will run for a much shorter period of time before the breaker turns off again.

Because of the location of the shore power I have no choice but to run two standard 30 amp power cords connected in series. I thought that the breaker might be weak because of its age, so I replaced it with a new 20 amp breaker identical originally installed. Unfortunately this did not solve the problem. When the compressor turns on the amp meter momentarily kicks up to between 15 to 18 A but then drops down to the normal draw of approximately 10 – 11 A. The onboard voltmeter shows an input of 120 V. My next step is to replace the onboard receptacle, although there are no obvious signs of corrosion or burning. But before I proceed I would like to get your thoughts on correcting this problem.

Thanks in advance.
It would be helpful to know the make of the AC Unit. When you purchased the boat, I suspect the seller may have included quite a file of "Ship's Papers" that may include the paperwork on the AC. If not, you might contact the Seller to see if he/she may still have anything, or remembers the name/date of the machine. Alternately, if you have access to the machine the makers name will likely be listed on a placard somewhere.

N'any case, based upon my own similar experience I suspect you may have a build-up of debris in the heat exchanger that is preventing the machine from shedding heat to the raw water. If you have one, an infrared thermometer will let you measure the temperature difference between the intake water and discharge water. On our 16,000 BTU unit, for example there is about a 12º or greater temperature rise in the discharge water. If not, the flow may not be sufficient causing a steady temperature rise in the compressor circuit, making the compressor overwork and draw greater amperage until it blows the circuit. The same could be true if you are low on freon but, if so, you would likely find ice forming on the radiator grid that actually cools the air which could also lead to a high temp/high pressure failure in the compressor. Cleaning out the heat exchanger coils is not a difficult job and there are several threads here abouts that describe the methods. Replacing freon will be a job for a technician unless you have those skills.

I note that you are located in Southwest Florida. If in the Tampa Bay area, there are several good AC mechanics that might be able to assist you, if necessary.

FWIW...
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