the a/c condenser can clog up with dirt, leaves, bugs and so on. spray it with degreaser from the bumper side, then hose it out by spraying the hose from inside the engine bay through the rad and a/c condenser first to wash it. then you can hose it from the out side in. do not brush it or touch it, you'll just bend the fins.

if you find a lot of dirt and crap on the ground afterwards that could have been the issue.