NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [WITH WU-TWC]


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


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.
1		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. (See KOEO/KOER SELF-TEST.) Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC test.
2		No	No DTC is displayed: Go to the next step.
3	Start the engine and idle it. Turn the A/C switch on. Does the A/C compressor engage?	Yes	Go to Step 5.
3		No	Inspect for the following and repair or replace if necessary: • Refrigerant charging amount • Open circuit between A/C relay and PCM terminal 1AL • 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 the ACSW PID. Start the engine and idle it. Turn the A/C switch on. Does the ACSW PID read "on"?	Yes	Go to the next step.
4		No	Inspect the following: • Refrigerant pressure switch operation • A/C switch is stuck open. • Open or short circuit between the refrigerant pressure switch and PCM terminal 1Q • Open circuit of blower motor fan switch and the resistor (if blower motor does not operate) • Evaporator temperature sensor and the A/C amplifier
5	Inspect the cooling fan control system operation. Does the cooling fan control system function properly?	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning parts.
6	Is the drive belt normal?	Yes	Go to the next step.
6	Is the drive belt normal?	No	Replace the drive belt.
7	Is there any leakage around the heater unit in passenger compartment?	Yes	Inspect the service heater for leakage.
7		No	Go to the next step.
8	Is there any leakage at the coolant hoses and/or radiator?	Yes	Replace the malfunctioning part.
8	Is there any leakage at the coolant hoses and/or radiator?	No	Go to the next step.
9	Cool down the engine. Remove the thermostat and inspect the operation. Is the thermostat normal?	Yes	If the engine coolant temperature and the thermostat are normal, inspect the engine block for leakage or blockage.
9		No	Access the ECT PID. Inspect both the ECT PID and temperature gauge readings. • If the temperature gauge in the instrument cluster indicates a normal range but the ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor. • If the temperature gauge in the instrument cluster indicates overheating but the ECT PID is normal, inspect the temperature gauge and the heat gauge units.
10	Verify the test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, inspect related Service information and perform repair or diagnosis. - If the vehicle is repaired, the troubleshooting is completed. - If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.