[racer]

Sounds like just a bad fan switch at the unit? Thus, only when you run the AC and get its condenser fan running do you get any cooling.

While your in there (front bumper cap removed) be sure to clean out all the road debris that collects down those cooling openings!

if the switch is open, you are merely giving the coolant a longer passage, but its not inherantly cooler. Getting the fan to turn on to blow air over the radiator is key.