overheat with A/C on???

Either high speed fan not working or the A/C is somehow heating the condenser too much.

Almost the same problem except my air doesnt turn off. My temps are fine in the city w/air off or on. However, on the highway it immediately jumps to the A-L on the temp gauge until the high temp fan kicks on. Now, this could be two things.
1) 10yr old radiator and water pump
2) I know I have a low charge on my AC due to a leak and from what I've been told is,,,this makes the compressor work harder creating more heat blowing on the radiator making that much harder for the car to cool down.
Im gonna try and remedy this by changing out the hose I know is leaking and cleaning out the motor/radiator by power flushing. Rather try this first instead of spending $350 on new Fluidyne radiator.

Air conditioning works by pulling the heat of out the incoming air to the car and rejecting it in front of the radiator. This means that now the radiator is trying to cool the engine in 120+* heat. Not a good situation for a marginal radiator. Also when the charge in an A/C system gets low it runs hotter and will trip the HPCO (high pressure cut out) switch to stop the system from blowing up.