a/c compressor is not getting 12v, where do I start?

[clydesdale]

When I press the button, I do not get 12v at the compressor. I jumped 12v to the compressor and it works. If I jumper the low/high pressure switch together, the compressor does not switch on and I do not get 12v at the low/high pressure switch. Where do I start? Thanks.

[Knockenwelle]

The A/C button. 90%...