NO.20 COOLING SYSTEM CONCERNS-RUNS COLD [MZR-CD (RF Turbo)]

id0103f1821800

20

COOLING SYSTEM CONCERNS-RUNS COLD

DESCRIPTION

•  Engine takes excessive period of time to reach normal operating temperature.

POSSIBLE CAUSE

•  Thermostat malfunction

•  Cooling fan system malfunction

•  Coolant heater system malfunction

20	COOLING SYSTEM CONCERNS-RUNS COLD
DESCRIPTION	• Engine takes excessive period of time to reach normal operating temperature.
POSSIBLE CAUSE	• Thermostat malfunction • Cooling fan system malfunction • Coolant heater system malfunction

Diagnostic Procedure

STEP	INSPECTION	RESULTS	ACTION
1	Is the customer complaint “Lack of passenger compartment heat”?	Yes	Inspect the A/C heater system.
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 [MZR-CD (RF-Turbo)]”. (See NO.9 SLOW RETURN TO IDLE [MZR-CD (RF Turbo)].)
2	Does the engine speed continue at fast idle?	No	Go to the next step.
3	Connect the M-MDS to the DLC-2. Access the ECT PID. Inspect the reading for both the ECT PID and the temperature gauge on instrument cluster. Is the ECT PID the same as the temperature gauge reading?	Yes	Go to the next step.
3		No	If the temperature gauge on the instrument cluster indicates a 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 a cold range but the ECT PID is normal, inspect the temperature gauge and the heat gauge unit.
4	Remove the thermostat and inspect the operation. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].) (See THERMOSTAT INSPECTION [MZR-CD (RF Turbo)].) Is the thermostat normal?	Yes	Go to the next step.
4		No	Replace the thermostat.
5	Perform the cooling fan control system Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD (RF Turbo)].) Does the cooling fan system work properly?	Yes	Perform the coolant heater system inspection. Repair or replace the malfunctioning part according to coolant heater system operation results.
5		No	Repair or replace the malfunctioning part according to inspection result.
6	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR-CD (RF Turbo)].) • If the malfunction remains, inspect the related Service Information and perform repair or diagnosis. ― If the vehicle is repaired, troubleshooting completed. ― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if later calibration is available. Retest.