Join Date: Mar 2006
Location: central ontario ( Parry Sound ) Canada
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Hey Tahiti Dave,
I'm not familiar with your unit however I am a refrigeration mechanic and I live on the Great Lakes in Canada. I have seen many marine units on power and sailboats. In general, charging for any unit is somewhat similar.
The vacuum pump is used to draw a vacuum on the system and can be attached to any port. In fact it is usually desirable to draw off both the high side and low sides of the system simultaneously. The purpose is to remove any non-condensables ( usually air ) and moisture or water vapour from the closed system prior to adding fresh refrigerant (or "charging ). I am assuming you have a "manifold" ( set of gauges ) in which to access the ports of your system.
The " high" side of the system usually is involved with the smaller lines and the larger lines are the " low" side of the refrigeration system. This should help you to identify the ports.
Once the system is evacuated with the vacuum pump, the system is sealed through the manifold valves and the vacuum pump removed from the manifold. Your new refrigerant tank is connected to the centre port of the manifold and the refrigerant line is purged back to the manifold line connection. Most times, the new marine refrigeration will operate on R134a refrigerant. This gas can easily be charged as a vapour and it is charged into the low side of the system. ( look for the port connnected to the larger line ) The easiest way to charge a system is to see if the manufacturer has a specification for the refrigerant charge by weight. If you have access to an accurate weigh scale, just set the tank on the scale and add refrigerant until the scale registers the correct weight and you are done.
In actuality, I have found marine units are nortorious for not including weight information. Unless the refrigeration unit is really small, add refrigerant vapour to the system until you have 35 psi showing on the gauge. Watch your gauge and start your system up. If the gauge goes up, stop the system and disconnect your gauge, ( you are on the wrong port ) Connect to the other port and repeat your test. The gauge should drop in pressure on the low side of the system with only vapour present in the system. Once the low side port connection is established, keep the refrigeration system running and add enough vapour just to keep the system out of a vacuum on the pressure gauge. Be patient as you are charging; add a little vapour and watch your gauge. As you add more refrigerant the cooling process will start in your cooler. Check the temperature with a thermometer and watch it cool down. The ultimate goal in charging is to have the cooler at proper temperature - 35 deg. F or 3 deg C and have approx 5 - 10 psi showing on your charging gauge. The large line( suction line ) should be just sweating and cold to to the touch( under any insulation ) back by the compressor. please note these value are for R134 refrigerant. If your system is not R 134, I can help you with other refrigerants as well.