NO.20 COOLING SYSTEM CONCERNS-RUNS COLD [MZR-CD 2.2]

id0103f3821800

20

COOLING SYSTEM CONCERNS—RUNS COLD

DESCRIPTION

•  Engine does not reach normal operating temperature.

POSSIBLE CAUSE

•  Thermostat malfunction

•  Cooling fan system malfunction

•  Coolant heater system malfunction

•  Improper indication of water temperature gauge

―  ECT sensor malfunction

―  Instrument cluster malfunction

20	COOLING SYSTEM CONCERNS—RUNS COLD
DESCRIPTION	• Engine does not reach normal operating temperature.
POSSIBLE CAUSE	• Thermostat malfunction • Cooling fan system malfunction • Coolant heater system malfunction • Improper indication of water temperature gauge ― ECT sensor malfunction ― Instrument cluster malfunction

Diagnostic Procedure

STEP	INSPECTION	RESULTS	ACTION
1	Is the customer complaint “Lack of passenger compartment heat”?	Yes	Inspect the A/C heater system. Repair or replace the malfunctioning part according to the inspection results.
1		No	Go to the next step.
2	Does the engine speed continue at fast idle?	Yes	Go to the symptom troubleshooting “NO.9 SLOW RETURN TO IDLE”. (See NO.9 SLOW RETURN TO IDLE [MZR-CD 2.2].)
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD 2.2].) Does the cooling fan control operate properly?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning part according to the inspection results.
4	Perform the coolant heater system inspection. (See WATER HEATER SYSTEM OPERATION CHECK [FULL-AUTO AIR CONDITIONER].) (See WATER HEATER SYSTEM OPERATION CHECK [MANUAL AIR CONDITIONER].) Does the coolant heater system operate properly?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning part according to the inspection results.
5	Inspect the thermostat. (See THERMOSTAT INSPECTION [MZR-CD 2.2]..) Is there any malfunction?	Yes	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD 2.2].)
5		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-CD 2.2].) ― Replace the ECT sensor if necessary. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR-CD 2.2].)
6	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR-CD 2.2].) • 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.