Compressor Clutch: Service and Repair
Vehicles using R-12
Vehicles using R-134a
DISASSEMBLY AND REASSEMBLY
SERVICE POINTS OF DISASSEMBLY
3. REMOVAL OF NUT
16. REMOVAL OF THERMOSTAT
In case of vehicles using refrigerant R-134a, remove the thermostat and revolution pick up sensor according to the following procedure:
(1) Remove the fitting block from the compressor.
(2) Remove the snap ring from the inside of the fitting block and remove the thermostat from the fitting block.
(3) Remove the revolution pick up sensor from the fitting block.
INSPECTION
- Check the surface of the armature for scoring or bluing.
- Check the surface of the rotor for scoring or bluing.
- Check the sealing surfaces for cracks, scratches and deformation.
- Check the front housing for cracks or scoring on the sealing surfaces.
- Check the compressor shaft for scoring.
HIGH PRESSURE RELIEF VALVE CHECK
The high pressure relief valve is a safe feature which releases part of the refrigerant inside the system into the atmosphere when the high pressure level exceeds 3.550 kPa (505 psi): R12, 3.740 kPa (532 psi): R-134a during air conditioning operation.
Once the pressure inside the system has been reduced to 2.400 kPa (341 psi): R-12, 2.940 kPa (418 psi): R-134a or lower, the high pressure relief valve closes. thus allowing continued operation.
(1) If a leak is detected at section A. replace the high pressure relief valve. The valve can be used unless there is a leak from that section.
(2) If a leak is detected at section B, retighten the valve. If the leak still persists after retightening the valve. replace the packing.
REFRIGERANT TEMPERATURE SENSOR CHECK
(1) Dip the refrigerant temperature sensor in engine oil.
(2) Check for continuity across terminals (1) and (2)
Standard value:
Continuity at approx. 110°C (230°F) or less at A point
No continuity at approx. 155°C (311°F) or more at B point
REVOLUTION PICK UP SENSOR CHECK
Measure the resistance between terminals (2) and (5) of the connector.
Normal resistance: 405±35 ohms when ambient temperature is 20°C (68°F)
If the measurement deviates greatly from the above resistance. replace the revolution pick up sensor assembly.
CONTROL VALVE CHECK
The control valve detects a low pressure level during the operation of the air conditioner. and adjusts the amount of refrigerant to be bypassed.
(1) Operate the air conditioning under a high temperature load condition (when vehicle interior temperature is high).
(2) Connect a low pressure gauge to the air compressor.
(3) Operate the air conditioning with the engine running at idle.
(4) Gradually increase the engine speed while observing the low pressure gauge.
If the valve is normal. the low pressure drops slowly as the engine speed increases until a pressure of 180 kPa (25 psi): R-12, 150-200 kPa (20-30 psi): R-134a is reached. at which point the pressure temporarily ceases to drop. Then. the pressure again starts dropping as the engine speed further increases.
If the valve is abnormal. the low pressure drops in direct proportion to the increase in engine speed without a temporary leveling off at the 180 kPa (25 psi): R-150-200 kPa (20-30 psi): R-134a pressure level. If the low pressure drops like this. replace the control valve.
SERVICE POINTS OF REASSEMBLY
17. INSTALLATION OF THERMOSTAT AND REVOLUTION PECK UP SENSOR
(1) Clamp the revolution pickup sensor and the thermostat in the fitting block, and then clamp the snap ring from the inside.
(2) Tighten the fitting block to the specified torque.
8. INSTALLATION OF CLUTCH COIL
(1) Align the pin of the clutch coil with the pin hole in the front housing, and then fit it into the hole.
(2) Install the snap ring so that the tapered surface is at the outer side.
4. INSTALLATION OF ARMATURE PLATE
Align the mating mark of the crankshaft spline and the mating mark of the armature plate, and then fit them together.
3. INSTALLATION OF NUT
AIR GAP ADJUSTMENT
Check whether or not the air gap of the clutch is within the standard value.
Standard value: 0.4-0.65 mm (.02- .03 in.)
NOTE: If there is a deviation of the air gap from the standard value. make the necessary adjustment by adjusting the number of shims.