Insufficient Cooling, No Cooling, Intermittent Cooling
Step 1: Checking refrigerant charge1. Run engine at a fast idle.
2. Operate air conditioner at maximum cooling for a few minutes, go to step 2.
Step 2: Checking refrigerant pressure
1. Connect A/C manifold gauge set.
2. Operate engine at 2,000 rpm and set air conditioner to maximum cooling.
3. Check for low-pressure and high-pressure.
Normal pressure:
Low-pressure side: 20 - 41 psi (137 - 284 kPa, 1.40 - 2.90 kg/sq.cm)
High-pressure side: 185 - 263 psi (1,275 - 1,814 kPa, 12.0 - 18.5 kg/sq.cm)
4. If pressures are not as specified, (refer to following chart and check system.)
Case 1: insufficient refrigerant
Measured pressure:
Low-pressure side: 8.5 - 14.2 psi (58.9 - 98.1 kPa, 0.6 - 1.0 kg/sq.cm)
High-pressure side: 119 - 136 psi (842 - 942 kPa, 8.4 - 9.6 kg/sq.cm)
CAUTION: Outlet air from vents is not cold.
Step 1
1. Check for oil stains on pipes, hoses and other parts.
2. If oil stains is found at connection of pipes or hoses, replace O-ring; then, evacuate, charge, and test system.
(Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
3. If oil stain is not found, go to step 2.
Step 2
1. Check for leakage from following connection with a gas leak tester.
a. Inlet and outlet of condenser
b. Inlet and outlet of receiver/drier
c. Inlet and outlet of compressor
d. 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 system. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
Step 3
1. Check tightening torque of connection where leak was detected.
2. If connection is loose, tighten connection to specified torque; then evacuate, charge, and test system. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
3. If connection is properly tightened, replace O-ring; then evacuate, charge, and test system. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
Case 2: Excessive refrigerant or insufficient condenser cooling
Measured pressure
Low-pressure side: 34.1 psi (235 kPa, 2.40 kg/sq.cm)
High-pressure side: 327 psi (2,256 kPa, 23.0 kg/sq.cm)
NOTE: If condenser fan does not operate when air conditioner is operating, (refer to "Condenser Fan Does Not operate" before proceeding.)
Step 1
1. Check condenser for bent fins or damage.
2. If condenser is OK, discharge excess refrigerant. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
CAUTION: Always wear gloves and eye protection when discharging refrigerant.
3. Verify that refrigerant pressure is normal.
Case 3: Air in system
Measured pressure
Low-pressure: Above 34.1 psi (235 kPa, 2.40 kg/sq.cm)
High-pressure: Above 377 psi (2,600 kPa, 26.5 kg/sq.cm)
Condition
Insufficient cooling
Step 1
Discharge refrigeration system. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
Step 2
Evacuate system to remove all air from it. (Refer to operating instructions of your refrigerant recovery/ recycling/charging station for proper procedures.)
Step 3
Charge system with refrigerant. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
Step 4
After charging, measure refrigerant pressure. (Refer to "Checking Refrigerant Pressure")
Step 5
If low-and high-pressure sides are still too high, replace receiver/drier.
Case 4: Moisture in system
Measured pressure
Low-pressure: Below 20 psi (137 kPa, 1.40 kg/sq.cm)
High-pressure: Below 88 psi (608 kPa, 6.20 kg/sq.cm)
CAUTION: 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 refrigeration system. (Refer to operating instructions of your refrigerant recovery/recycling/ charging station for proper procedures.)
Step 2
Evacuate system to remove all air and moisture from it. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
Step 3
Charge system with refrigerant. (Refer to operating instructions of your refrigerant recovery/recycling/ charging station for proper procedures.)
Step 4
After charging, measure refrigerant pressure. (Refer to "Checking Refrigerant Pressure".)
Step 5
If low-and high-pressure sides are still too high, replace receiver/drier.
Case 5: No refrigerant circulation
Measurement pressure
Low-pressure: Below 20 psi (137 kPa, 1.40 kg/sq.cm)
High-pressure: Below 88 psi (608 kPa, 6.20 kg/sq.cm)
CAUTION: Refrigerant flow obstructed by moisture or dirt, causing freezing or blockage Of expansion valve.
Step 1
1. Turn air conditioner OFF for about 10 minutes. Turn air conditioner ON to determine whether 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.)
b. If caused by dirt: System remains abnormal after being OFF 10 minutes. Go to Step 2.
Step 2
1. Remove expansion valve.
2. Blow out dirt with compressed air.
3. If unable to remove dirt, replace expansion valve.
4. Evacuate, charge, and test system. (Refer to operating instructions of your refrigerant recovery/recycling/charging station for proper procedures.)
Case 6: Expansion valve stuck open
Measured pressure
Low-pressure: Above 35.6 psi (245 kPa, 2.50 kg/sq.cm)
High-pressure: 307 - 326 psi (2,119 - 2,247 kPa, 21.6 - 22.9 kg/sq.cm)
CAUTION:
Insufficient cooling.
Step 1
1. Check whether there is frost or heavy dew on 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 expansion valve.
Case 7: Faulty compressor
Measured pressure
Low-pressure: 57 - 88 psi (392 - 608 kPa, 4.0 - 6.20 kg/sq.cm)
High-pressure: 107 - 152 psi (736 - 1,050 kPa, 7.50 - 10.7 kg/sq.cm)
CAUTION:
No cooling
Step 1
1. Run engine at a fast idle.
2. Verify that A/C compressor clutch is ON when A/C switch and blower switch are ON.
3. If A/C compressor clutch remains OFF, refer to "A/C Compressor Clutch does not operate".