2000 Sunfire A/C Problem

The A/C clutch needed replacing on this car; it was making a lot of noise when disengaged. It always engaged reliably though when the dash A/C switch was pressed. I took the car into the shop and they put on a remanufactured clutch assembly. However, when I pressed the A/C switch on the dash the clutch sometimes wouldn't engage and the engine cooling fan also wouldn't come on. The mechanics decided the clutch assembly was defective and put on another at no cost. However, the same thing is happening. I decided to do some checking myself. Measuring voltages at the clutch relay I found when the clutch didn't engage the PCM was not gounding the clutch relay coil; the PCM is not allowing the A/C to operate even though the A/C switch is on. I did one more test and unplugged the clutch relay. With the engine running I jumpered the 12V battery contact to the clutch coil contact. The clutch engaged and also the engine cooling fan came on. I'm at a loss to explain how the PCM determined it should turn on the cooling fan. Can anyone familiar with the A/C system on this car tell me what might be the problem here? Thanks, Mike