RING-SEAL 7G9968 - Caterpillar

Caterpillar Machines Equipped With Air ConditioningReference: The Mobile Air Conditioning Society Worldwide, Inc., P.O. Box 100, East Greenville, PA 18041, "MACS Service Reports", March 1996
Effective July 1, 1992 regulations prohibit the venting of any refrigerant into the atmosphere. Refer to Caterpillar publications SENR3334-01, SENR5664 and NEDG5065-01 for the proper procedure, equipment and tools to reclaim refrigerant from any Caterpillar machine.
Always wear goggles when working on air conditioning systems. The system is under pressure at all times, engine running or not. Escaping refrigerant R-12 (C C12F2Dichlorodifluoromethane) and refrigerant R-134a can cause freezing of human flesh. Do not smoke while working on air conditioning. Inhaling refrigerant R-12 or R-134a through any smoking material, although not toxic or flammable, can cause violent illness. Also heat must never be applied to a charged system. See Air Conditioning And Heating Service Manual SENR3334-01 and SENR5664, for more information on removal and installation of lines and refrigerant from the system.
Contaminated air conditioning refrigerant is becoming a more common source of poor air conditioning system performance. In CFC-12 based systems there are no Caterpillar approved alternative refrigerants other than completely converting to a HFC-134a based system. In the CFC-12 based systems some of the sources of contamination are unapproved refrigerants such as R-22, and some flammable refrigerants. Another source of contamination is from air leaking into the system and from air introduced through the use of recycled CFC-12. These contaminants can be detected with the use of a refrigerant identifier such as the 138-6629 Identifier, the 139-2610 Identifier, or the 139-2611 Identifier. The maximum allowable amount of NCG (non-condensable gases) in an CFC-12 system is 1.5 percent.
Refer to Chart 1 and Chart 2 to see the effects of contaminates on the pressure/temperature ratios within the system.
Chart 1. This MACS chart shows how pressures rise from under 634 kpa (92 psi) at 29.4°C (85°F) with pure CFC-12, up to 703 kpa (102 psi) with about 1.5% air contamination, the maximum tolerable amount of NCG (non-condensable gases, basically air). Next, the chart shows how the CFC-12 pressures rise from contamination with 2% HFC-134a or 2% HCFC-22, then 5% HFC-134a or 5% HCFC-22, and finally with 10% HFC-134a or 10% HCFC-22.
Chart 2. This MACS chart shows how pure HFC-134a compares with the same types of contamination, in this case with CFC-12 and HCFC-22, also at 29.4°C (85°F). The pressure of pure HFC-134a is just over 648 kpa (94 psi). With about 2% contamination by air (NCG), the pressure rises to 689 kpa (100 psi). Next, the chart shows how HFC-134a pressures rise from contamination with 2% CFC-12 or 2% HCFC-22, then 5% CFC-12 or 5% HCFC-22, and finally with 10% CFC or 10% HCFC-22.As shown in Chart 1 and Chart 2, contaminated refrigerant can generate abnormal pressure readings. Refrigerant temperature/pressure charts indicate the pressure of a pure refrigerant for a specific temperature (see Chart 3 and Chart 4). When an air conditioning system is turned off, temperature and pressure will equalize throughout the system. If the pressure readings