NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [WITHOUT WU-TWC]


18	COOLING SYSTEM CONCERNS -RUNS COLD
DESCRIPTION	The engine takes excessive period to reach normal operating temperature.
POSSIBLE CAUSE	• Thermostat malfunction • Condenser fan system malfunction • Cooling fan system malfunction


STEP	INSPECTION	RESULTS	ACTION
1	Is the customer complaint "Lack of passenger compartment heat" only?	Yes	Inspect A/C and heater system.
1		No	Go to the next step.
2	Does the engine speed continue at fast idle?	Yes	Go to symptom troubleshooting "No.9 Fast idle/runs on".
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Remove the thermostat and inspect the operation. (See THERMOSTAT REMOVAL/INSTALLATION [ZJ, ZY].) (See THERMOSTAT INSPECTION [ZJ, ZY].) Is the thermostat normal?	Yes	Go to the next step.
3		No	Replace the thermostat.
4	Inspect the cooling fan control system operation. (See Cooling Fan Control System Inspection.) Does the cooling fan control system work properly?	Yes	Access ECT PID. Inspect both the ECT PID and temperature gauge on the instrument cluster 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 cold range but the ECT PID is normal, inspect the temperature gauge and heat gauge units.
4		No	Repair or replace the malfunctioning part.
5	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, replace or reprogram the PCM.