NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [YF (2.0L Zetec)]


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 • 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 using the WDS or equivalent. Are any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [YF (2.0L Zetec)].)
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 the following and repair or replace if necessary: • Refrigerant charging amount • Open circuit in wiring harness between A/C relay and PCM terminal 69 • 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 ACCS PID. Start the engine and idle it. Turn the A/C switch on. Does the ACCS PID read "On"?	Yes	Go to the next step.
4		No	Inspect the following: • Refrigerant pressure switch operation • The A/C switch is stuck open. • Open or short circuit between refrigerant pressure switch and PCM terminal 41 • Open circuit of blower motor fan switch and resistor (if blower motor does not operate) • The evaporator temperature sensor and A/C amplifier
5	Inspect cooling fan control system operation. (See Cooling Fan Control System Operation Inspection.) Does the cooling fan control system function properly?	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning part.
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 leakage around the heater unit in the passenger compartment?	Yes	Inspect and service the heater for leakage.
7		No	Go to the next step.
8	Is there leakage at the coolant hoses or radiator?	Yes	Replace the malfunctioning part.
8	Is there leakage at the coolant hoses or radiator?	No	Go to the next step.
9	Cool down the engine. Remove the thermostat and inspect operation. (See THERMOSTAT INSPECTION [YF (2.0L Zetec), AJ (3.0L Duratec)].) Is the thermostat normal?	Yes	The ECT sensor and thermostat are normal. Inspect 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 on the instrument cluster indicates normal range but the ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor. • If the temperature gauge on the instrument cluster indicates overheating but the ECT PID is normal, inspect the temperature gauge and heat gauge unit.
10	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [YF (2.0L Zetec)].) • If any malfunction remains, inspect related service information and, repair or diagnosis accordingly. - If the vehicle is repaired, troubleshooting completed. - If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [YF (2.0L Zetec)].)