A/C Clutch makes noise

[Dayz]

Guys,
My A/C compressor clutch doesn't engage. I don't have A/C. Also, my vacuum pump doesn't work, therefore the selector switch is stuck on defrost. I just realized that my compressor clutch is "clicking" even when I am on full heat, no A/C.

What could be my problem, can I just change parts and not the whole compressor? Could it be something else.

Point me in the right direction,
Thanks
Dayz