I have problem with the AC compressor in my 2004 kia carnival which was working fine until i swaped the engine in the local workshop. I checked all fuses they are seems to be good. I tried to wire the compressor directly to the car’s battery and the clutch engaged. What do you think the problem is?
Do you have refrigerant in the system? It may have leaked out if a pipe was nudged during the engine change. If refrigerant is low, the AC compressor will never be given the Turn On signal from the ECU.
The fact that the compressor runs when you give it power directly indicates that you're not suffering from compressor clutch wear.