Insufficient Cooling

TROUBLE DIAGNOSIS

Insufficient Cooling

SYMPTOM: Insufficient cooling

INSPECTION FLOW


1. CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - TEMPERATURE DECREASE

1.Turn temperature control dial counterclockwise to maximum cold position.
2.Check for cold air at discharge air outlets.
Can the symptom be duplicated?
YES- GO TO 3.
NO- GO TO 2.

2. CHECK FOR ANY SYMPTOMS

Perform a complete operational check for any symptoms. Operational Check.
Does another symptom exist?
YES- How To Perform Trouble Diagnosis For Quick And Accurate Repair.
NO- System OK.

3. CHECK FOR SERVICE BULLETINS

Check for any service bulletins.
- GO TO 4.

4. CHECK COMPRESSOR DRIVE BELT TENSION

Check compressor belt tension. Procedures (MR-20DE) or Procedures Adjustments Removal And Installation, "Checking Drive Belts" (QR-25DE).
OK or NG
OK- GO TO 5.
NG- Adjust or replace compressor belt. Adjustments (MR-20DE) or Adjustments (QR-25DE).

5. CHECK AIR MIX DOOR OPERATION

Check and verify air mix door mechanism for smooth operation in each mode.
Does air mix door operate correctly?
YES- GO TO 6.
NO- Repair or replace as necessary.

6. CHECK COOLING FAN MOTOR OPERATION

Check and verify cooling fan motor for smooth operation. Engine Controls For California (MR-20DE) or
(QR-25DE).
Does cooling fan motor operate correctly?
YES- GO TO 7.
NO- Check cooling fan motor. Engine Controls For California (MR-20DE) or , "System
Description" (QR-25DE).

7. CHECK RECOVERY/RECYCLING EQUIPMENT BEFORE USAGE

Check recovery/recycling equipment before connecting to vehicle. Verify there is no pressure in the recovery/
recycling equipment by checking the gauges. If pressure exists, recover refrigerant from equipment lines.
- GO TO 8.

8. CHECK REFRIGERANT PURITY

1.Connect recovery/recycling equipment to vehicle.
2.Confirm refrigerant purity in supply tank using recovery/recycling and refrigerant identifier.
OK or NG
OK- GO TO 9.
NG- Check contaminated refrigerant. Contaminated Refrigerant.

9. CHECK FOR REFRIGERANT PRESSURE

Check refrigerant pressure with manifold gauge connected. Refer to "TEST READING".
OK or NG
OK- Perform diagnostic work flow. Refer to "DIAGNOSTIC WORK FLOW".
NG- GO TO 10.

10. CHECK FOR EVAPORATOR FREEZE UP

Start engine and run A/C. Check for evaporator freeze up.
Does evaporator freeze up?
YES- Perform diagnostic work flow. Refer to "DIAGNOSTIC WORK FLOW".
NO- GO TO 11.

11. CHECK AIR DUCTS

Check ducts for air leaks.
OK or NG
OK- If the symptom still exists, perform a complete operational check. Operational Check. If other symptoms exist, How To Perform Trouble Diagnosis For Quick And Accurate Repair.
NG- Repair air leaks.

DIAGNOSTIC WORK FLOW






















PERFORMANCE CHART

Test Condition
Testing must be performed as follows:






TEST READING

Recirculating-to-discharge Air Temperature Table





Ambient Air Temperature-to-operating Pressure Table






TROUBLE DIAGNOSIS FOR ABNORMAL PRESSURE

Whenever system's high and/or low side pressure is abnormal, diagnose using a manifold gauge. The marker above the gauge scale in the following tables indicates the standard (normal) pressure range. Since the standard (normal) pressure differs from vehicle to vehicle, refer to Ambient Air Temperature-to-operating Pressure
Table above.
Both High- and Low-pressure Sides are Too High





High-pressure Side is Too High and Low-pressure Side is Too Low





High-pressure Side is Too Low and Low-pressure Side is Too High





Both High- and Low-pressure Sides are Too Low





Low-pressure Side Sometimes Becomes Negative





Low-pressure Side Becomes Negative