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refrigeration companies offer different methods of servicing their units. I use a coverall refrigerant servicing method on systems with capillary tube refrigerant flow control and the Danfoss BD compressors. This 30 year old Adler
service bulletin still works today.
Knowing compressor model and module number will make fine tuning refrigerant later much easier?
It sounds like there is presently some refrigerant in this unit. Your first step is to check for leaks by adding refrigerant gas vapor only with unit not running. Bottle refrigerant pressure on a warm day should raise pressure in system to a range from 55psi to 65 psi adequate for basic leak testing.
These are the steps needed on a BD2, BD2.5, BD35 or BD50 compressor capillary Tube unit to re-commission your system:
Note this servicing procedure should not be used on TXV or Eutectic Holding plates. If you need help with off brand compressors check system manufactures web site
repair Bulletins instructions.
1. Check gauge set to see that gauges read zero when not attached to unit if not adjust or make a note of their errors.
2. With both gauge hand valves closed, connect 134a bottle to center yellow hose. Check to see that blue gauge has blue hose and lose end of blue hose has a valve
core depressor inside. Before connecting blue hose to low pressure connection open blue gauge valve for 2 seconds to purge yellow and blue hose then close valve and connect blue hose to
service fitting on top of compressor.
Inspect valve cap you removes to see that rubber seal inside cap is still good. Slow leaks are sometimes traced to a bad cap seal.
3. With refrigerant bottle upright open blue gauge valve to add refrigerant. Blue gauge should now be reading system pressure of 30 to 60 psi depending on temperature of complete system. After blue gauge is connected and system has pressure in it you will need a one inch
paint brush and a small amount of water and liquid dishwashing soap mixed 50/50% to locate refrigerant leak.
4. With 50 psi of gas pressure in system, use soap and water mixture to locate leak. By using brush to apply mixture to only one point at a time stabbing brush into location until a shaving cream mixture surrounds it you will break down to liquid surface tension so any leak must come through foam generating bubbles. Leak testing is done with compressor off.
5. After leak is found and repaired unit can be serviced with correct amount of refrigerant. In your situation best way to get correct charge is again raise pressure 50 psi then run compressor for 10 minutes and then and only then add refrigerant if necessary or reach 6 to 8 psi suction pressure. It is important that you not add refrigerant after 20 minutes run time as correct pressure can not be determined after 20 minutes. For final fine tuning unit needs to run for a day or more. Correct refrigerant charge for your unit is when 90 to 100% of evaporators surface is covered with frost and no frost on line outside
refrigerator on line returning to compressor.