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.