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 (HR16DE) or (MR18DE).
OK or NG
OK - GO TO 5.
NG - Adjust or replace compressor belt. Removal and Replacement (HR16DE) or Removal and Replacement (MR18DE).
5.CHECK AIR MIX DOOR CABLE
Check and verify air mix door cable operation. Air Mix Door Cable Adjustment.
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. P1217(MR18DE) or P1217 (HR16DE).
Does cooling fan motor operate correctly?
YES - GO TO 7.
NO - Check cooling fan motor. P1217 (MR18DE) or P1217 (HR16DE).
7.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 8.
8.CHECK REFRIGERANT PRESSURE
Check refrigerant pressure with manifold gauge connected. Refer to "PERFORMANCE CHART".
OK or NG
OK - GO TO 9.
NG - Perform diagnostic work flow. Refer to "DIAGNOSTIC WORK FLOW".
9.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






TEST READING
Recirculating-to-discharge Air Temperature Table





Ambient Air Temperature-to-operating Pressure Table





*1: With blower control dial in the "1" position
*2: With blower control dial in the "4" position.

TROUBLE DIAGNOSIS FOR ABNORMAL PRESSURE
Whenever system's high and/or low side pressure(s) is/are abnormal, diagnose using a manifold gauge. The marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the standard (usual) pressure, however, differs from vehicle to vehicle, refer to above table (Ambient air temperature-to-operating pressure table).

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