NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR 1.8, MZR 2.0, MZR 2.5]

id0103d4802300

17

COOLING SYSTEM CONCERNS—OVERHEATING

DESCRIPTION

•  Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

•  Radiator hoses damage

•  Coolant leakage

―  Leakage around heater unit

―  Leakage at coolant hoses and/or radiator

•  Improper coolant level

•  Fans reverse rotation

•  Fuse malfunction

•  Coolant overflow system malfunction

•  Poor radiator condition

•  Improper or damaged radiator cap

•  Improper water/anti-freeze mixture

•  PCM DTC is stored

•  Improper operation of A/C system

―  Climate control unit malfunction (A/C switch malfunction or climate control unit does not determine A/C request or transmit the A/C request signal)

―  Refrigerant pressure switch malfunction

•  Improper operation of cooling fan control system

•  Improper tension of drive belt

•  Thermostat malfunction

•  Improper indication of water temperature gauge

―  ECT sensor malfunction

―  Instrument cluster malfunction

17	COOLING SYSTEM CONCERNS—OVERHEATING
DESCRIPTION	• Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE	• Radiator hoses damage • Coolant leakage ― Leakage around heater unit ― Leakage at coolant hoses and/or radiator • Improper coolant level • Fans reverse rotation • Fuse malfunction • Coolant overflow system malfunction • Poor radiator condition • Improper or damaged radiator cap • Improper water/anti-freeze mixture • PCM DTC is stored • Improper operation of A/C system ― Climate control unit malfunction (A/C switch malfunction or climate control unit does not determine A/C request or transmit the A/C request signal) ― Refrigerant pressure switch malfunction • Improper operation of cooling fan control system • Improper tension of drive belt • Thermostat malfunction • Improper indication of water temperature gauge ― ECT sensor malfunction ― Instrument cluster malfunction

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: • Collapsed or restricted radiator hoses • Coolant leakage • Engine coolant level • Fan rotational direction • Fuses • Overflow system • Radiator condition • Radiator pressure cap • Water and anti-freeze mixture Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
1		No	Go to the next step.
2	Perform the PCM DTC inspection using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 1.8, MZR 2.0, MZR 2.5].) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [MZR 1.8, MZR 2.0, MZR 2.5].)
2		No	Go to the next step.
3	Perform the KOEO or KOER self test. (See KOEO/KOER SELF TEST [MZR 1.8, MZR 2.0, MZR 2.5].) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [MZR 1.8, MZR 2.0, MZR 2.5].)
3		No	Go to the next step.
4	Start the engine and run it at idle speed. Turn the A/C switch off. Does the A/C compressor disengaged?	Yes	Go to the next step.
4		No	Perform the symptom troubleshooting “NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”. (See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR 1.8, MZR 2.0, MZR 2.5].)
5	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].) Does the cooling fan control system operate properly?	Yes	Go to the next step.
5		No	Repair or replace the malfunctioning part according to the inspection results.
6	Inspect the drive belt. (See DRIVE BELT INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].) Is there any malfunction?	Yes	Replace the drive belt. (See DRIVE BELT REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].)
6		No	Go to the next step.
7	Inspect for leakage around heater unit in passenger compartment. Is there any leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results.
7		No	Go to the next step.
8	Inspect for leakage at coolant hoses and/or radiator. Is there any leakage?	Yes	Repair or replace the malfunctioning part according to the inspection results.
8		No	Go to the next step.
9	Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 1.8, MZR 2.0, MZR 2.5].) Compare the ECT PID and water temperature gauge readings. Is the ECT PID value same as water temperature gauge readings?	Yes	Go to the next step.
9		No	Inspect the water temperature gauge. (See INSTRUMENT CLUSTER INSPECTION.) • If there is any malfunction: ― Repair or replace the malfunctioning part according to the inspection results. • If there is no malfunction: ― Inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].) ― Replace the ECT sensor if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].)
10	Cool down the engine. Remove the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].) Inspect the thermostat operation. (See THERMOSTAT INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].)
10		No	The engine coolant temperature and thermostat are normal. • Inspect the engine block for leakage or blockage. • Repair or replace the malfunctioning part according to the inspection results.
11	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 1.8, MZR 2.0, MZR 2.5].) • If the malfunction remains, inspect the related Service Information and perform the repair or diagnosis. ― If the vehicle is repaired, troubleshooting is completed. ― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.