The electric fan is the a/c condenser fan and is controlled by the high-pressure switch on the a/c drier, so it was not designed to aid in engine cooling. The engine fan has a viscous drive that may be your problem. If there is an accumulation of dirt due to the loss of viscous fluid at the hub, then I would replace it.

After I installed the winch I seemed to notice an air flow problem at a stop. The a/c would not cool as well but the condenser fan was on. I installed an after market electric fan on the left side of the radiator that took care of the a/c problem as well as running a bit hot on the trail. I have never had a problem on the road no matter what temperature.
Todd