Just bought the car used a few months ago. A/C worked fine but it wasnt hot outside. Now that its hot, its slowly gotten warm. It would take a while to get cool, and even then it wouldnt cool very well. Now it just blows warm air. Both cooling fans are working. Compressor IS kicking on.

It has a sight glass mounted on top of the drier. With the a/c running and the van up to temp, the sight glass appears milky or cloudy. I understand this normally means low freon charge. So I purchased a can of R134A that has a low pressure side gauge on it. I hooked it up, and it reads 45psi, overchaged. Hmm. Now what? Is the milkyness oil? What should I do? I cant afford to take it to a shop right now. I was hoping for an easy fix. I am a mechanic, but have no A/C experience or access to any A/C equipment.

If it is Milky or foamy looking in the site glass, I suspect the system is Low on R-134. The high (45psi) pressure in the low side could be caused by a Bad Expansion valve that is stuck wide open, or a bad compressor.
If the expansion valve is stuck wide open the A/C will not get very cold.

ac is not a do it yourself project. you need to evacuate the system, vacuum the system, and put proper amount of refrigerant in the system. do that then edit your question and give high and low side readings so we can help.