Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

NO. 18 COOLING SYSTEM CONCERNS - RUNS COLD [AJ] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	Is customer complaint "Lack of passenger compartment heat" only?	Yes	Inspect A/C and heater systems.
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 ".
2	Does engine speed continue at fast idle?	No	Go to the next step.
3	Remove thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION .) (See THERMOSTAT INSPECTION .) Is thermostat okay?	Yes	Go to the next step.
3		No	Replace thermostat. (See THERMOSTAT REMOVAL/INSTALLATION .)
4	Inspect fan control system operation. Does fan control system work properly?	Yes	Access ECT PID using WDS or equivalent. Inspect for both ECT PID and temperature gauge on instrument cluster readings. If temperature gauge on instrument cluster indicates normal range but ECT PID is not same as temperature gauge reading, inspect ECT sensor. If temperature gauge on instrument cluster indicates cold range but ECT PID is normal, inspect instrument cluster and related harnesses.
4		No	Repair or replace malfunctioning part.
5	Verify test results. If okay, return to diagnostic index to service any additional symptoms. If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, reprogram PCM if later calibration is available. Retest.