Just my gut feeling but I doubt that the fan would be PWM modulated. Only time that would make sense would be if it was running on a PID loop and I dont think they are trying to control engine temp that carefully. Unless they were doing a soft start or something.
Easy way to tell should be by the number of connections. If the connector has 3 terminals its most likely designed for PWM and if only 2 its probably not.
They run the headlights with it, so I could see them using it on the fan as well. The wife has our Jeep today because of the snow, but I will check when she gets home.