Air Conditioning and Heating R-12 All Caterpillar Machines – General Information

------ WARNING! ------

Personal injury can result from contact with refrigerant.

This system is under pressure at all times, even if the engine is not running. Heat should never be applied to a charged system.

Contact with refrigerant can cause frost bite. Keep face and hands away to help prevent injury.

Protective goggles must always be worn when refrigerant lines are opened, even if the gauges indicate the system is empty of refrigerant.

Always use caution when a fitting is removed. Slowly loosen the fitting. If the system is still under pressure, evacuate the system recovering the refrigerant before removing the fitting.

Personal injury or death can result from inhaling refrigerant through a lit cigarette.

Inhaling air conditioner refrigerant gas through a lit cigarette or other smoking method or inhaling fumes released from a flame contacting air conditioner refrigerant gas, can cause bodily harm or death.

Do not smoke when servicing air conditioners or wherever refrigerant gas may be present.

Before any checks of the air conditioning and heating system are made, move the machine to a smooth horizontal surface. Lower all implements to the ground. Make sure the transmission is in neutral or park and that the parking brake is engaged. Keep all other personnel away from the machine or where they can be seen.


  • All refrigerant lines that are metal or flexible hose must be free of sharp bends. Also, do not use a refrigerant line that is kinked. Sharp bends will cause a restriction in the refrigerant flow. Restrictions in the refrigerant lines are identified by cold spots or frost on the line at the location of the restriction. Restrictions in the lines reduce the performance and the efficiency of the system.

  • The radius of bends in the flexible hose must never be less than 10 times the outside diameter of the hose.

  • Do not allow the flexible hoses to come within 63.5 mm (2.50 inch) of the exhaust manifold.

  • The hoses need to be inspected yearly for leaks and for hardness. Conduct a leak test on all the hoses and the lines. Refer to the Service Manual, SENR3334, “Refrigerant Leakage – Test” section in testing and adjusting. Replace hoses if leaks or hardness are in the hoses. Replace hoses with new hose that is sealed and free of contaminants.

  • The correct use of wrenches is very important when connections are made. The type of wrench that is used is also important. Only use wrenches that are made for use with tube type fittings. When a hose is connected or disconnected from the system, use a wrench on the fitting and use a wrench on the nut. When a metal line is connected or disconnected from the system, use a wrench on the fitting and use a wrench on the nut.

  • Install protective plugs or protective caps on all components and hoses that are disconnected or removed.

  • O-ring seals and O-ring seats must be in good condition. Small cuts, scratches, or particles of dirt will cause a leak in the system. Put new refrigerant oil on all new O-ring seals at the time of installation. Do not use any kind of sealant on connections.

  • Dust caps on the compressor block fittings are the primary seals on the air conditioning system.

  • All machines should have an identification tag that specifies the refrigerant charge for the machine. The tag should be located in the operator compartment.

  • If water is in the vents check the nonreturn valve. If water leaks from the air conditioning system, check the nonreturn valve. The nonreturn valve should have the proper position and the proper direction.

  • If engine coolant is leaking into the operator compartment, check for loose clamps on the heater hoses.

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