A/C Not powering and clicking sound in cabin

I have a 2001 Saturn L200. My A/C doesn’t work. My dad is a retired old school mechanic and can’t figure it out. The compressor turns on, on occasion, we think it’s not getting power because we connected the compressor directly to the battery and it turns on fine. Think it’s some type of electrical issue. Also hear a clicking sound inside the cabin when I depress the brakes when my gear shift lights are off. Sometimes they work and doors lock automatically when I put it in drive, but other times the lights don’t work and I get that clicking and my doors don’t lock. I believe the issue is electrical and tied together with a/c issues, but have no idea where to look. Any suggestions? Thanks

It could be that the A/C compressor is not engaging because the system is low on refrigerant. There are usual several pressure switches involved which activate or shut off the compressor depending upon what the pressures are doing.

As fro the gear shift lights and door locks I do not know. Does the clicking come under the dash or seats? Clicking generally means a relay is kicking in and out. That could be because the relay has aged with burned contact points in it or some other electrical gremlin in the relay trigger circuit is causing it to kick in and out. (Poor connection, etc.)

I have no schematics for Saturns at all. I’ll take a look at the near worthless AutoZone site and see if their help section has one.

Agree it could be low pressure but I’ve also had a bad pressure switch too that made the system think it was low. It was a hot 200 mile drive.