A/c Help

[81_Chevy]

so my truck has "factory" a/c. my dad swapped the old r12(not sure what the old stuff was called) to the new R134 type a/c from a 1985 about 10 years ago. he said it used to work great then just stopped working. well this last summer (2012) i tried to recharge it and i found out that my clutch doesnt ingage on the compressor. i also heard a leak from a line somewhere. i followed the green wire to the high side line where it connects to something on the line and then changes into a green w/ white stripe wire. on the wire with green and white i have power. but after that theres no power going to the compressor to engage it.

i know the compressor works cuz i cut the line and hooked it up to my battery (was already cut before) and it engaged.
im just curious to know if there is a bad thing on the high side line? (not sure what its called) ill try to find a pic of it. i believe its called the regulator.
also is it worth just to take my truck to a shop and have it overhauled or just do it myself?
thanks in advance -Nic

[pcguysam]

With patience, you can hopefully fix the A/C problem yourself.  Eric the car guy has some pretty good videos you can check out.  There are a couple on AC:
http://www.youtube.com/watch?v=CVMWW95E7qk&list=PL034A0CBCE388E429

First, foremost and SUPER IMPORTANTLY, you should NEVER vent coolant into the atmosphere(it's the law and a pretty stiff one).

Secondly, you'll need some tools to do the job:
Harbor freight has a sale on the gauge manifold for $45 right now.  Normally $70 there and over $100 at most places.
http://www.harborfreight.com/a-c-manifold-gauge-set-92649.html

They also have a good deal on a vacuum pump if you have access to a compressor that will push at least 90PSI, this is the way to go for $19.
http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html

If you don't have a compressor, a vacuum pump with one can be had for $99:
http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html

If you heard a leak the first thing for you to do is to find the leak.  Autozone should sell everything you need for leak detection.  Being able to hear it doesn't sound like it will be hard to find.  If you run the compressor with no coolant/oil, you'll burn it up, so be careful. 

The UV dye you need to pinpoint the leak:
http://www.autozone.com/autozone/accessories/Quest-2-1-oz-5-shot-R134a-UV-dye/_/N-265k?itemIdentifier=424627_0_0_

What you need to detect the die:
http://www.autozone.com/autozone/accessories/Quest-UV-pen-light-with-batteries-and-glasses/_/N-265k?itemIdentifier=424631_0_0_

[muddnutz]

If there is a low pressure switch it won't let clutch engage until pressure builds up

[Sartobuilt]

Fix the leak. Charge the system and when there is enough pressure the switch will engage the compressor.

[81_Chevy]

hmm, okay. thanks for the posts everybody. so im guessing since there was a leak there is no pressure in the lines thus not letting the pressure switch open which would explain the clutch not engaging. hmmm