Help diagnosing A/C issue

I've tried searching on A/C* and "air* conditioning" and haven't had any luck.

I'm trying to track down an issue with an intermitent A/C issue. When the knob is set to both normal and high A/C it only works maybe 25% of the time. When it does work it blows very cold air, so I don't think it's low on r134. To me this just seems like an electrical problem and not a hardware problem.

Autozone.com shows a $5.99 compressor relay, so I'm wondering if swaping it out might fix things. Or, I wonder if the high/low limit switch is going out.

Has anyone run into this issue on their car and if so how did you fix it? Is there anything I can jump to force the compressor on and try to find the issue that way? And if it turns out the issue is with the high/low limit switch is it in direct contact with the system (IE: I take if off and I would have to have the system pulled down and refilled w/ r134) or is it seperate and removing it won't open up the system?

Thanks!

I kept digging for answers using search and found a link to the following document:

http://renaxgade.net/95ac.pdf

This looks like it has some good info. Anyone know where the cycling switch is located?

I have a refill kit at home that I just tried using on our old 99 Contour that has a gauge on it. I'll have to try hooking that up just to see what it reads.