NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [L3]

BME010300000W19

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 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 okay?
Yes
Go to next step.
No
Service as necessary.
Repeat Step 1.
2
Connect WDS or equivalent to DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
Are there any DTCs displayed?
Yes

DTC is displayed:

Go to appropriate DTC test.
No

No DTC is displayed:

Go to next step.
3
Start engine and run it at idle speed.
Turn A/C switch on.
Does A/C compressor engage?
Yes
Go to Step 5.
No
Inspect for following and repair or replace as 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 okay, go to next step.
4
Connect WDS or equivalent to DLC-2.
Access ACSW PID.
Start engine and run it at idle speed.
Turn A/C switch on.
Does ACSW PID read ON?
Yes
Go to next step.
No
Inspect 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 cooling fan control system operation.
Does cooling fan control system work properly?
Yes
Go to next step.
No
Repair or replace malfunctioning parts.
6
Is drive belt okay?
Yes
Go to next step.
No
Replace drive belt.
7
Is there any leakage around heater unit in passenger compartment?
Yes
Inspect and service heater for leakage.
No
Go to next step.
8
Is there any leakage at coolant hoses and/or radiator?
Yes
Replace malfunctioning part.
No
Go to next step.
9
Cool down the engine.
Remove thermostat and inspect operation.
Is thermostat okay?
Yes
Engine coolant temperature and thermostat are okay, inspect engine block for leakage or blockage.
No
Access ECT PID.
Inspect for both ECT PID and temperature gauge readings.
If temperature gauge on instrument cluster indicates normal range but ECT PID is not same as temperature gauge reading, inspect ECT sensor.
If temperature gauge on instrument cluster indicates overheating but ECT PID is normal, inspect temperature gauge and heat gauge unit.
10
Verify test results.
• If okay, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM.