Start by checking the high and low pressures could be a freon problem
June, 5, 2011 AT 10:56 PM
Check the quantity of the refrigerant if its low then the a/c compressor won't work. The compressor should have a relay change that as well
June, 14, 2011 AT 7:24 PM
You will need to use a manifold gauge set to perform the tests mentioned above. Their are two different sized valves in the A/C lines that correspond to high side (after the compressor) and low side (before the compressor). You shouldn't be able to connect them incorrectly. As stated, if there isn't enough refrigerant (R134a in 2004) in the system, the compressor won't cycle.
However, from your description of the problem, it sounds to me like either the clutch is defective or the clutch relay is defective. Both of these items can have internal problems that make them nonfunctional only when hot, since heat causes metallic components to expand and components made from different types of metals will expand at different rates. If you can do so SAFELY, put a meter on the electrical connector on the compressor and see if it is being energized. Also, find the A/C relay and make sure it is being energized properly.