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

id0103008024c6

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

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Is the customer complaint "Lack of passenger compartment heat" only? | Yes | Inspect A/C and heater system.
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".
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.
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.
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.