NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [L3]

BME010300103255

17

COOLING SYSTEM CONCERNS -OVERHEATING

DESCRIPTION

Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

• Improper coolant level
• Blown fuses
• Coolant leakage
• Excessive A/C system pressure
• A/C system operation is improper
• Improper water/anti-freeze mixture
• Fans reverse rotation
• Poor radiator condition
• Thermostat malfunction
• Radiator hoses damage
• Condenser fan is inoperative.
• Improper or damaged radiator cap
• Cooling fan is inoperative.
• Coolant overflow system malfunction
• Improper tension of drive belt
• Drive belt damage

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Inspect the following:
• Engine coolant level
• Coolant leakage
• Water and anti-freeze mixture
• Radiator condition
• Collapsed or restricted radiator hoses
• Radiator pressure cap
• Overflow system
• Fan rotational direction
• Fuses
Are all items normal?
Yes
Go to the next step.
No
Service if necessary.
Repeat Step 1.
2
Connect the WDS or equivalent to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
Are there any DTCs displayed?
Yes

DTC is displayed:

Go to the applicable DTC inspection.
No

No DTC is displayed:

Go to the next step.
3
Start the engine and run it at idle speed.
Turn the A/C switch on.
Does the A/C compressor engage?
Yes
Go to Step 5.
No
Inspect for the following and repair or replace if necessary:
• Refrigerant charging amount
• Open circuit between A/C relay and PCM terminal 4O
• Seized A/C magnetic clutch
• A/C magnetic clutch malfunction
If all items are normal, go to the next step.
4
Connect the WDS or equivalent to the DLC-2.
Access AC_REQ PID.
Start the engine and run it at idle speed.
Turn the A/C switch on.
Does AC_REQ PID read ON?
Yes
Go to the next step.
No
Inspect the following:
• Refrigerant pressure switch operation
• A/C switch is stuck open.
• Open or short circuit between refrigerant pressure switch and PCM terminal 1AC
• Open circuit of blower motor fan switch and resistor (if blower motor does not operate)
• Evaporator temperature sensor and A/C amplifier
5
Inspect the cooling fan control system operation.
Does the cooling fan control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part.
6
Is the drive belt normal?
Yes
Go to the next step.
No
Replace the drive belt.
7
Is there any leakage around the heater unit in passenger compartment?
Yes
Inspect and service the heater for leakage.
No
Go to the next step.
8
Is there any leakage at the coolant hoses and/or the radiator?
Yes
Replace the malfunctioning part.
No
Go to the next step.
9
Cool down the engine.
Remove the thermostat and inspect the operation.
Is the thermostat normal?
Yes
The engine coolant temperature and the thermostat are normal.
Inspect the engine block for leakage or blockage.
No
Access ECT PID.
Inspect for both ECT PID and the temperature gauge readings.
If the temperature gauge on the instrument cluster indicates normal range but ECT PID is not the same as temperature gauge reading, inspect the ECT sensor.
If the temperature gauge on the instrument cluster indicates overheating but ECT PID is normal, inspect the temperature gauge and the heat gauge unit.
10
Verify test results.
• If normal, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM.