The fan speed is controlled by the cooling fan ECU. It is not adjustable. Here is how it all works:
The Cooling Fan ECU receives various signals, i.e, the engine RPM signal from the Ignitor, engine idle speed signal from the Throttle Position Sensor, Coolant Temperature signal from the Engine Coolant Temperature Sensor (Water Temperature Sensor), A/C Refrigerant Pressure Signal from A/C Pressure SW.
The Cooling fan ECU judges the Engine temperature based on the above-mentioned signals drives the Solenoid Valve and controls the speed of the Cooling Fan.
Do you hear the fan speed increase as the engine temp increases?
I attached the diagnostics for the cooling fan ECU in the pics below. Here is a link you may find helpful:
The last pic below shows the location of the cooling fan ECU.
I hope this helps. Let me know if you have other questions.
See pics below.
Images (Click to enlarge)
Monday, May 3rd, 2021 AT 7:26 PM