electric cooling fans

[Richard]

Good to the see the full amp draw does not change with the PWM setup was mentioned. With PWM control you get less heat at motor with variable speed or lower speed set points. There is some heat generated at controller. It is much less than a variable voltage setup though because voltage remains constant @ 12v.
A few remarks- note that typically a lower watt fan (lower amp draw) will move less air. With a good fan setup you do not necessarily needs fan/fans at full speed with A/C on. Am using a single oem 850 watt 19" PWM fan on my truck. The PWM signal is coming from the stock e67 ECU. A pressure sensor in the A/C lines sends information to ECU which will command fan @ 50% duty cycle when it is required. This method only turns fan on when needed, when pressure rises. ie- low speed or around town driving. Fan really not needed at highway speed. The duty cycle (fan speed) will change with engine cooling needs as well. The higher speed always takes priority.