Yes, if you have the slim fan hooked up to the radiator fan plug but mounted on the ac side it will still act as a radiator fan. Whether or not it cools the radiator is if it on the surface of the radiator; this depending if you have a dual core or a single core radiator. Regardless, if it's not mounted on or above the surface of the radiator, it WILL NOT help with cooling.
The fans should work interchangeably. You can simply just switch the plugs from each fan without remounting each fan unless you want the slim fan as your primary radiator fan.
Also, when you were waiting for the fan to turn on at operating temperatures; did you reinstall the radiator cap? If you didn't then the radiator fan will not turn on.
Assuming you did reinstall the radiator cap after bleeding and waiting for he fan to turn on but it didn't. Then you should re-check the connections between the fan and the plugs. Also, check the fan switch plug ( plug on the thermostat housing). In addition, inspect your radiator cap to see if it's still good. A bad radiator cap will not adequately hold pressure and will not kick up the fans.