Pusher fan is a last resort.
Useful for cooling an A/C condenser in conjunction with a puller on the back side of radiator. Puller (for radiator) cycles on/off with thermostat as needed, pusher for condenser cooling is on anytime compressor cycles or as dictated by 3 wire pressure switch so as to keep the psi of A/C system within reason and add life to it. If your condenser doesn't get enough air, the pressure will get too high and damage things...expensive things. Adding a pusher is a cheap and smart way to avoid trouble.
