If equipment is still operational, record initial baseline
data for later comparison. This would consists of the following:
System operating temperatures and pressures
Voltages and running amperages
Superheat and sub-cooling net temperatures
Ambient temperatures and humidity.
Estimated % load condition
Step 2
If the existing equipment is already charged with AB (alkylbenzene
oil) or is a small packaged system with a mineral oil charge, oil change
is not required. For medium to larger systems, perfom a complete oil
change to AB if mineral oil is known to be in the system. The goal is to
achieve a minimum of 50% AB to ensure proper oil return. A single oil
change will typically result in a 50%-80% charge of AB and 20%-50% mineral
oil lubricant base.
Step 3
Recover CFC refrigerant from the system and weigh the amount
removed.
Step 4
Replace the filter/drier
Step 5
Evacuate system to 500 microns. Ensure
that the system is free of leaks.
Step 6
Charge the system with 75% of original refrigerant charge by
weight. Remember to charge liquid only from the
cylinder.
Step 7
Start up the system and allow time for conditions to
stabilize. Record operating conditions and compare to original baseline
recordings if possible. Adjust charge as required up to approximately 90%
or the original charge. Do not overcharge the
system.
Step 8
Make sure to label all system components with the new
refrigerant and total charge.
