Air Conditioning and Heating R-12 All Caterpillar Machines – Refrigerant Expansion Valve – Remove and Install

To replace the expansion valve, use the procedure that follows. Refer to Service Manual, SENR3334, “Troubleshooting Heating and Air Conditioning Control System” before service work is performed on the air conditioning system.

  1. Recover the refrigerant.

    Note: Cap all disconnected lines and hoses.

  1. Remove the insulation and the clip. The insulation and the clip hold the sensing bulb to the evaporator outlet pipe.
  1. Disconnect the sensing line for pressure from the evaporator outlet pipe.
  1. Loosen and remove the two connections at the expansion valve. Remove the expansion valve.

    Note: Check the O-ring seals. The seals must be in good condition and the seals must be properly lubricated with the correct refrigerant oil before assembly.

  1. Install the expansion valve for replacement and tighten the two connections.
  1. Tighten the pressure sensing connection on the evaporator outlet pipe.
  1. Use a 8P-6355 Clip to hold the sensing bulb onto the evaporator outlet pipe. The sensing bulb should be as close to the coil as possible. The bulb should be upstream of the pressure sensing connection on the evaporator outlet pipe. The 5P-7070 Insulation should be wrapped tightly around the clip, the sensing bulb and the outlet pipe. There should be no insulation between the bulb and the outlet pipe.
  1. Tighten all the connections correctly.
  1. Evacuate the system. Refer to the Service Manual, SENR3334, “Refrigerant System – Evacuate” section in testing and adjusting.
  1. Charge the system with the correct amount of refrigerant by weight. Refer to the Service Manual, SENR3334, “Refrigerant System – Charge” section in testing and adjusting.
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