NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [ZJ, Z6]


18	COOLING SYSTEM CONCERNS - RUNS COLD
DESCRIPTION	Engine takes excessive period for reaching normal operating temperature.
POSSIBLE CAUSE	• Thermostat malfunction • Condenser fan system malfunction • Cooling fan system malfunction


STEP	INSPECTION	RESULTS	ACTION
1	Is customer complaint "Lack of passenger compartment heat" only?	Yes	Inspect A/C and heater system.
1		No	Go to the next step.
2	Does engine speed continue at fast idle?	Yes	Go to symptom troubleshooting "No.9 Fast idle/runs on". (See NO.9 FAST IDLE/RUNS ON [ZJ, Z6].)
2	Does engine speed continue at fast idle?	No	Go to the next step.
3	Remove the thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION [ZJ, Z6].) (See THERMOSTAT INSPECTION [ZJ, Z6].) Is the thermostat normal?	Yes	Go to the next step.
3		No	Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [ZJ, Z6].)
4	Inspect cooling fan control system operation. (See Cooling Fan Motor Operation Inspection.) Does cooling fan control system work properly?	Yes	Access ECT PID. Inspect for both ECT PID and the temperature gauge on the instrument cluster readings. • If the temperature gauge on instrument cluster indicates normal range but ECT PID is not same as the temperature gauge reading, inspect the ECT sensor. • If the temperature gauge on the instrument cluster indicates cold range but ECT PID is normal, inspect the temperature gauge and the heat gauge unit.
4		No	Repair or replace the malfunctioning part.
5	Verify test results. • If normal, return to diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [ZJ, Z6].) • If malfunction remains, inspect related Service information perform repair or diagnosis. - If vehicle repaired, troubleshooting completed. - If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [ZJ, Z6].)