Insufficient Cooling. No Cooling. Intermittent Cooling
Symptom: Insufficient cooling. No cooling. Intermittent cooling.Step 1 Checking refrigerant charge
1. Run the engine at a fast idle.
2. Operate the air conditioner at maximum cooling for a few minutes.
3. Observe the sight glass to determine the amount of refrigerant and the related action as shown below.
Step 2 Checking refrigerant pressure
1. Connect the A/C manifold gauge set.
2. Operate the engine at 2,000 rpm and set the air conditioner to maximum cooling.
3. Measure the refrigerant pressure.
Normal pressure
Low-pressure side: 196 - 294 kPa (2.0 - 3.0 kg/cm2, 28 - 43 psi)
High-pressure side: 1,373 - 1,570 kPa (14.0 - 16.0 kg/cm2, 199 - 228 psi)
4. If the pressures are not as specified, refer to the following chart and check the system as indicated.
Case 1: Insufficient refrigerant
Measured Pressure
Low-pressure side: Less than 78.5 kPa (0.8 kg/cm2, 11.4 psi)
High-pressure side: 785 - 883 kPa (8 - 9 kg/cm2, 114 - 128 psi)
Condition:
^ Outlet air from vents not cold.
^ Bubbles seen in sight glass.
Step 1
1. Check for oil stains on the pipes, hoses and other parts.
2. If oil staining is found at the connection of pipes or hoses, replace the 0-ring; then, evacuate, charge, and test the system.
3. If oil staining is not found, go to Step 2.
Step 2
1. Check for leakage from the following connections with a gas leak tester
^ Inlet and outlet of condenser.
^ Inlet and outlet of receiver/drier.
^ Inlet and outlet of compressor.
^ Sight glass.
^ Inlet and outlet of cooling unit.
2. If leakage is evident, go to Step 3.
3. If leakage cannot be found, evacuate, charge, and test the system. (System OK, but refrigerant leaked gradually over time.)
Step 3
1. Check tightening torque of the connection where leak was detected.
2. If the connection is loose, tighten the connection to the specified torque; then evacuate, charge, and test the system.
3. If the connection is properly tightened, replace the 0-ring; then evacuate, charge, and test the system.
Case 2: Excessive refrigerant or insufficient condenser cooling
Measured Pressure
Low-pressure side: Above 245 kPa (2.5 kg/cm2, 35.6 psi)
High-pressure side: Above 1,962 kPa (20 kg/cm2, 284 psi)
Condition: Insufficient cooling
Note If the condenser fan does not operate when the air conditioner is operating, see "Symptom: Additional (Condenser) Fan Does Not Operate".
Step 1
1. Check the condenser for bent fins or damage. Repair or replace if necessary.
2. If the condenser is OK, go to Step 2.
Step 2
1. Discharge the excessive refrigerant.
Warning: Always wear gloves and eye protection when discharging the refrigerant.
2. Verify that the refrigerant pressure is normal.
Case 3: Air in system
Measured Pressure
Low-pressure side: Above 245 kPa (2.5 kg/cm2, 35.6 psi)
High-pressure side: Above 2,256 kPa (23 kg/cm2, 327 psi)
Condition: Insufficient cooling
Step 1
Discharge the refrigeration system.
Step 2
Evacuate the system to remove all air from it.
Step 3
Charge the system with refrigerant.
Step 4
After charging, measure the refrigerant pressure.
Step 5
If low- and high-pressure sides are still too high, replace the receiver/drier.
Case 4: Moisture in system
Measured Pressure
Low-pressure side: 50 cm Hg (2.0 in Hg): [Vacuum]
High-pressure side: 687 - 1,472 kPa (7 - 15 kg/cm2, 100 - 213 psi)
Condition: Intermittent cooling
(Moisture in refrigeration system freezes in expansion valve and causes temporary blocking. After time, ice melts and condition returns to normal.)
Step 1
Discharge the refrigeration system.
Step 2
Evacuate the system to remove all air and moisture from it.
Step 3
Charge the system with refrigerant.
Step 4
After charging, measure the refrigerant pressure.
Step 5
If low- and high-pressure sides are still too high, replace the receiver/drier.
Case 5: No refrigerant circulation
Measured pressure
Low-pressure side: 76 cm Hg (3.0 in.Hg) [Vacuum]
High-pressure side: Below 589 kPa (6 kg/cm2, 85 psi)
Condition:
Refrigerant flow obstructed by moisture or dirt, causing freezing or blockage of expansion valve.
Step 1
Turn the air conditioner OFF for about 10 minutes. Turn the air conditioner ON to determine whether the blockage is due to moisture or dirt.
a) If caused by moisture, system will operate normally after being OFF for 10 minutes. (Ice melts and relieves blockage.)
Refer to "Moisture in system".
b) If caused by dirt, system remains abnormal after being OFF 10 minutes. Go to Step 2.
Step 2
1. Remove the expansion valve.
2. Blow out the dirt with compressed air.
3. If unable to remove the dirt, replace the expansion valve.
4. Evacuate, charge, and test the system.
Case 6: Expansion valve stuck open
Measured pressure
Low-pressure side: Above 245 kPa (2.5 kg/cm2, 35.6 psi)
High-pressure side: 1,864 - 1,962 kPa (19 - 20 kg/cm2, 270 - 284 psi)
Condition: Insufficient cooling
1. Check whether there is frost or heavy dew on the suction pipe (between cooling unit and compressor).
2. If neither is found, refer to "Case 2: Excessive refrigerant or insufficient condenser cooling".
3. If either is found, replace the expansion valve.
Case 7: Faulty compressor
Measured pressure
Low-pressure side: 392-589 kPa (4-6 kglcm2, 57-85 psi)
High-pressure side: 687-981 kPa (7-10 kg/cm2, 100-142 psi)
Condition: No cooling
1. Run the engine at a first idle.
2. Verify that the magnetic clutch is ON when the A/C switch and blower switch are ON.
3. If the magnetic clutch remains OFF, refer to "Symptom: Magnetic Clutch Does Not Operate".