How long does the compressor run before it shuts down? If it runs for only a minute or so its more than likely a bad run capacitor. Being low on refrigerant usually won't cause the compressor to over heat. The other problem that might cause it to trip on internal overload is a fouled condenser. Also check the sea strainer if its partially plugged that will cause low water flow.
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The refrigerant type will be listed on the units data plate. If its older than 5 years more than likely it will be charged with R-22 if its a newer unit it will be 410-A or R134-A. I just priced R-22 for a chiller repair and dealer cost on a 30 pound can is $788.00. I would recommend to have a qualified technician check it out to make sure whats going on with it.
Thank you for the help, last year it was working somewhat but this year doesn't work at all it runs for about 3 minutes and shots compressor off I checked it the unit and the compressor gets very hot and causes the thermal switch on top of the compressor to trip off, how do I determine what type of freon it needs fi was to try to recharge it
I do have few cans of r22 that I purchased last month from E bay .the unit has two port whit brass caps on it, one is labeled as a suction I suppose that's where gets charged, I am familiar with Automotive units
It more than likely has R-22. The symptoms you describe its not likely to be low on refrigerant, It sounds like an electrical problem. Low refrigerant can cause compressor over heating but that usually occurs after a long run and after it shuts off with high suction super heat temps. I would start by checking all electrical connections and water flow.
If those are good I would check the compressor start components such as the start and run capacitors and the start relay if so equipped.
I just hooked up the gauge and Freon can to the suction side but I didn't not punched the can it is still sealed and noticed the Gauge in about 3 minutes the needle goes all the way over to the max 360 degrees and the compressor shuts off also noted the water Cooling discharge coils are getting very hot
If you have a set refrigeration gauges I would hook em up and check the pressures before adding refrigerant. Over charging a system is actually worse than under charging and can cause damage. Also make sure you have a temperature pressure chart and check your condensing water temps and evaporator entering air temps.
If your condenser is overheating, check your temperature difference of the cooling water into and out of the condenser. Verify water flow out through the hull. If you have an infra red temperature sensor, check the freon temp inlet and outlet of the condenser and compare the difference. The gas outlet should be quite cool. I'm guessing you have a clogged or scaled up condenser.
From the original nameplate on my Marine Air Systems from 1989, it's R-22 in the unit. The 16,000 BTU aft unit has 16 oz for a charge.
If the 3818 is like the 32, there is a magnetic water pump near the strainer. If you have one, you can tell if this is the problem right away by putting your hand on it after you hear the compressor shut down. If it's hot, you have found the problem. The replacement is like 2- 3 hundy or you can take it apart and make sure the impellers are clear.
My 1989 Marine Air AC in the main salon of my 3818 started shutting off last summer, similar to this. Although there was still some water flow, it was constricted. I had just gotten the boat, so I had to poke around a bit to find the sea strainer (under the hatch in the main stateroom). The sea-strainer was almost totally clogged up, and a live crab had moved in. I set him free (I'm sure it was a pretty comical site with me running thru the cabin with one hand under the sea-strainer to try to not drip gunk everywhere, and one finger of the other hand trying to poke the crab back into the sea-strainer without him grabbing my finger...that would have been a youtube moment, methinks), cleaned the sea-strainer (attach one of those little keyring floats to it if you're hosing it off outside...drop it in the water without it and it's gone!), stacked 5-6 bromine tablets in the sea-strainer (at the recommendation of several of my dock neighbors)...voila. I clean that sea-strainer about every 10 days or so of run-time...seems to be necessary in my location.
Start with the easy stuff...check the sea-strainer if you haven't already.
Hot water discharge indicates not enough water flow as above, and also the unit has enough refrigerant in it to make the condenser discharge hot. Clean the water circuit but be prepared for a possible compressor failure in the near future once you get it going.