NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZI-3.7]

id0103d2802300

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

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

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.
1		No	Service if necessary. Repeat Step 1.
2	Connect the M-MDS to the DLC-2. Turn the ignition switch to the ON position (Engine off). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7].)
2		No	No DTC is displayed: Go to the next step.
3	Start the engine and idle it. Turn the A/C switch on and set blower fan to any speed. 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 in wiring harness between A/C relay and PCM terminal 1N • Seized A/C magnetic clutch • A/C magnetic clutch malfunction If all items are normal, go to the next step.
4	Connect the M-MDS to the DLC-2. Access AC_REQ PID. Start the engine and idle it. Turn the A/C switch and fan switch on. Does AC_REQ 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 1R • 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 ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7].) 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 passenger compartment?	Yes	Inspect and service heater for leakage.
7		No	Go to the next step.
8	Is there leakage at the coolant hoses and/or radiator?	Yes	Replace the malfunctioning part.
8	Is there leakage at the coolant hoses and/or radiator?	No	Go to the next step.
9	Cool down the engine. Remove thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION [MZI-3.7].) (See THERMOSTAT INSPECTION [MZI-3.7].) Is thermostat normal?	Yes	The engine coolant temperature and thermostat are normal, inspect engine block for leakage or blockage.
9		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 CHT 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 normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].) ― If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZI-3.7].)