Air Conditioning and Heating R-12 All Caterpillar Machines – Visual Inspection

------ 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.


Before you conduct a performance check of the air conditioning system, the following items should be checked:

  1. Check the condenser and the evaporator.
    1. Check for any type of restriction that will obstruct the air flow. Check for dirt, insects, plastic bags, etc.
    1. For machines that are equipped with condensers that are mounted on the roof, always make sure that all fan motors are running. Check for restrictions. A clean condenser will lead to longer life for the compressor.
  1. Clean the fresh air filters and clean the recirculation filters.
  1. Check for a loose belt on the compressor.
  1. Check the moisture indicator, if equipped. If the indicator is pink or white, there is moisture in the system. Replace the receiver-dryer or the in-line dryer. Refer to the proper Disassembly and Assembly manual for your machine. If the moisture indicator is blue, the system is normal.
  1. Check the drain tube on the evaporator. The drain plug should not be obstructed.
  1. For machines that are equipped with an accumulator, start the machine. Set the air conditioner on HIGH. Feel the accumulator with the hand. In a properly charged system, the entire accumulator will be cool to the touch or cold to the touch.
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