The Condenser fan is designed to move air across/through the A/C condenser which sits in front of your radiator. While it is large enough to 'aid' in the heat exchange for that item (condenser) it would have negligible effect on the cooling system of your vehicle.
It is normal to experience a slight increase in engine/coolant temps during prolonged stops (perhaps as much as 6-8°F in severe heat). During slow speeds and stops you don't have the benefit of 'ram air' going through the A/C condenser, radiator and across the engine/transmission. So the evacuation of under-hood heat becomes less effective. The engine cooling fan alone bears all the burden in those conditions.
Also, during slow speeds/stops.... engine rpm is less, so by default there is less cooling going on as the engine cooling fan (mechanical) is simply not spinning as fast, nor is your water pump. Yes, the engine is not working as hard either, but 'heat soak' can begin to happen quite rapidly under hood.... even having been stopped just a few minutes.
It is vital that your cooling SYSTEM be in top shape for summertime heat. In short, a condenser fan simply can not contribute enough to engine cooling to be considered a reason to install one or suspect it as a possible reason for increased coolant temps.
BUT......the opposite is most certainly true. IF your cooling system is not performing well you'll have engine/transmission/under-hood heat build up, which WILL effect your A/C systems ability to cool.
