Cooling Fan Control System Inspection
WARNING: This page is about a different car, the 2004 Mazda 6 and 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
- Verify that the battery voltage is more than 12.4 volts. If the battery voltage is less than 12.4 volts, charge the battery or connect the external power supply.
- Connect the Worldwide Diagnostic System (WDS), or equivalent scan tool, to the DLC-2 located under left side of instrument panel and access ECT PID. See Fig 1.
- Turn A/C switch to OFF position.
- Verify ECT PID is less than 209°F (98°C). If ECT PID more than 209°F (98°C), inspect ECT sensor and related wiring harnesses.
- Verify that the cooling fan does not operate with ECT PID is less than 209°F (98°C) while the ignition switch is ON position. If the cooling fan operates, inspect for following parts and related wiring harnesses:
- ECT sensor.
- A/C switch.
- A/C refrigerant pressure switch (high/low pressure).
- A/C refrigerant pressure switch (medium pressure).
- Vehicle Speed Sensor (VSS).
- A/C magnetic clutch.
- Fan control signal circuit between fan control module harness connector terminal "B" and PCM terminal 1W (Blue wire). See Fig 2.
If the all items are normal, replace fan control module.
- Verify the cooling fan operates while the A/C switch to ON with the ignition switch at ON position. If the cooling fan does not operate, inspect the following:
- A/C switch.
- A/C refrigerant pressure switch (high/low pressure).
- Fan control module power supply circuit.
- Fan control module GND circuit.
- Fan control signal circuit between fan control module harness connector terminal "B" and PCM terminal 1W (Blue wire). See Fig 2.
If all items are normal, replace fan control module.
- Verify battery voltage exists at PCM harness connector terminal 1R (Black/Green wire) and the cooling fan operates at medium speed with the A/C refrigerant pressure switch is in a medium pressure condition. See Fig 2. If cooling fan does not operate as specified, check A/C pressure switch operation. See appropriate AUTOMATIC or MANUAL A/C-HEATER SYSTEMS article in HVAC. If A/C pressure switch is operating properly, replace fan control module.
- Turn A/C switch to off.
- Start the engine and let idle.
- Verify that the cooling fan operating speed increases relative to ECT PID increases. If the cooling fan speed does not increase inspect following:
- ECT sensor (characteristics). See ENGINE COOLANT TEMPERATURE SENSOR under COMPONENT TESTS.
- Fan control signal circuit between fan control module terminal "B" and PCM terminal 1W (Blue wire). See Fig 2.
If the all items are normal, replace fan control module.