Here is a description of the cooling fan system.
Powertrain Control Module (PCM) regulates radiator cooling fans with Pulse Width Modulated (PWM) signals to solid state radiator fan relay. Radiator fan relay control circuit supplies 12-volt signal to PCM. PCM then pulses ground circuit to achieve fan activation. Radiator fan relay provides voltage to fan motors that is proportional to pulse width received from PCM. Duty cycle ranges from 30 percent for low speed fan operation and 100 percent for high speed fan operation. This type of fan control system provides infinitely variable fan speeds, allowing for improved fan noise, A/C performance, better engine cooling, and additional vehicle power.
Operation of radiator fan relay by PCM is based on inputs from engine coolant temperature sensor, A/C pressure transducer, ambient air temperature from body control module, vehicle speed, and transmission oil temperature. PCM uses these inputs to determine when fans should operate and at what speed.
There is a possibility of the PCM being the cause of the overcooling.
Tuesday, December 21st, 2010 AT 1:41 PM