TRANSMISSION 4M8265 - Caterpillar

Note: The electrical power supply to the compressor should be switched OFF in order to perform this test.
Test the rotation. Rotate the compressor in the direction of belt travel by turning the nut on the end of the main shaft of the compressor. Rotation should be smooth with no binding.Rotation Checked ? Yes or No.Rotation Smooth? Yes or No.
Check the charge level. Charge the air conditioning system as per Caterpillar specification or an incorrect diagnosis will occur. Recovering, evacuating, and recharging with clean refrigerant to the correct level is the best method of achieving the correct refrigerant charge for the system. Charging the air conditioning system must be conducted by weighing refrigerant with a calibrated scale in order to ensure accuracy. Also, be sure to replace the oil which was removed during refrigerant recovery with new oil. Reference Specifications, "Refrigerant Compressor" for procedures regarding refrigerant charging and capacity of Caterpillar air conditioning systems.Charge Level Checked ? Yes or No.Volume of Oil that was Removed During Recovery: ____ (ml) or (oz) Weight of Refrigerant Charge: ____ (Kg) or (lbs)
Test for low pressure. The test for low pressure should be performed with ambient temperatures of less than 30 °C (86 °F). Park the machine in an area that is not in direct sunlight. Close all cab doors and windows. Block the flow of fresh air into the cab. If the air conditioning system is so equipped, bypass the low-pressure switch . Start the machine. Operate the machine at high idle. Turn ON the air conditioning. Set the cab blower on LOW. After 10 to 15 minutes of operation, measure the low-side pressure at the refrigerant compressor. If the pressure reading is less than 69 kPa (10 psi), then the suction valves of the compressor are operating correctly.Low Pressure Checked ? Yes or No.Low Pressure Reading: ____ (kPa) or (Psi) Note: If the cab temperature is above 25 °C (77 °F), the set the cab blower to HIGH in order to reduce the temperature before starting the procedure.
Test for high pressure. Start the engine and set the speed at approximately 1200 rpm. Turn ON the air conditioning. Place a sheet of cardboard over the condenser in order to block the flow of air. Limiting the flow of air over the condenser will cause the discharge pressure of the compressor to increase. Check if the discharge of the compressor is able to increase up to 2414 kPa (350 psi). Once the specified pressure is reached, immediately remove the cardboard. If the compressor passes the test, the discharge valves are operating correctly.High Pressure Checked ? Yes or No.High Pressure Reading: ____ (kPa) or (Psi) The functional test is now complete. If this test procedure results in inconclusive results, your dealership Technical Communicator can report the problem by using the on-line Dealer Solution Network. The Dealer Solution Network will provide your Technical Communicator with additional troubleshooting support.Illustrations 1 through 4 are provided as Good Air Conditioning System Practices and Troubleshooting Tips.
Illustration 1 g01127048
3E-1906 Refrigerant Compressor