I just installed an A/C on my 1986 Toyota Pickup, this may sound dumb but forgive me haha... I have not charged the A/C yet, or vacuumed but I figured I would see if the compressor would turn on but it doesn't the amplifier under the dash makes a click noise but that's it... Does it need to have pressure In order for the amp to read it has pressure so it turns on the compressor and everything else? Please someone help me out just hope the amp or something isn't bad thanks guys!

 

The system has to see pressure to kick to compressor on and off. This is done via the high pressure switch. You need to charge the ac system and then try to cut it on. If it doesn't turn on then you have another issue

 

If you vacuumed the system really good and it holds vacuum then you should be able to hook up a can of 134 and the A/C lines vacuum suck in enough to start cycling the compressor one. Be sure you have the A/C on and on high speed when you start filling. Or you can just engage the A/C compressor by touching the A/C trigger wire to the battery. That will engage the compressor and suck in freon. Either way, yeah, you need some freon pressure in there for the compressor to come on.

 

It would be a real good idea to pull a vacuum.

Make sure you don`t have leaks.

you did use all new parts??