Cooling Fan Control System Inspection

WARNING: This page is about a different car, the 2004 Mazda 3. 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 V .
- If the battery voltage is less than 12.4 V , charge the battery or connect the external power supply.
Connect the WDS or equivalent and access ECT PID.
Turn A/C switch to off.
Verify ECT PID is less than 98 °C {209 °F} .
- If ECT PID more than 98 °C {209 °F} , inspect ECT sensor and related wiring harnesses.
Verify that the cooling fan does not operate with ECT PID is less than 98 °C {209 °F} while the ignition switch is ON.
- 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).
  - VSS.
  - A/C magnetic clutch.
  - Fan control signal circuit (between fan control module terminal B and PCM terminal 1W).
    - 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 for 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 terminal B and PCM terminal 1W).
    - If the all items are normal, replace fan control module.
Verify that the cooling fan operates as specified. See Fig 1.
- If the cooling fan operation is not specified, inspect for following:
  - A/C refrigerant pressure switch (Medium pressure).
    - If the A/C refrigerant pressure switch (Middle pressure) is normal, replace fan control module.
Fig 1: Cooling Fan Operation Specifications
Courtesy of MAZDA MOTORS CORP.
Turn A/C switch to off.
Start the engine and idle it.
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 (characteristic).
    (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION .)
  - Fan control signal circuit (between fan control module terminal B and PCM terminal 1W).
    - If the all items are normal, replace fan control module.