savegoodautonfg said:
it may have been swapped to a 134a but if it was how can i tell?
If it was done properly, it would have the correct fittings on the hi and low side.
It appears that you are asking how to rebuild an engine, then telling that you don't know what a spark plug is. First, I suggest that you read the below link, especially the section on the basics of the Fox A/C system. You need to understand the basics of the system before you start to work on it. Pressurized refrigerant can blind you in a split second if you do not know what you are doing.
Next, I suggest that if it sounds like it is too much for you to learn to troubleshoot (people here have already told you how), then you should take it to a shop that advertises they do A/C work.
Last, if you do want to try and troubleshoot it, I suggest that you start off with checking the wires for insulation burn at the WOT relay. This is the small rectangular relay mounted on the front of the passenger-side shock tower. If all looks good, start the engine and turn on the A/C, disconnect the LPCS and jumper the wire connector to see if the compressor turns on. If it does, this tells you the system is working electrically. It also tells you that you have an issue with either a bad LPCS or your refrigerant is low. Do not leave the compressor going like this for more than 60 seconds or you start to endanger the expensive compressor. If you do start getting cold (not cool) air, you need a new LPCS (~$37 at Ford last time I bought one). If you do not get cold air, your refrigerant is low.
If your refrigerant is low, you need to decide to stay with R12, or convert over to R134A. The link I gave lines out a procedure that I have helped a few hundred people convert with. My Mustangs are blowing 42 degrees on 93 degree ambient days. If you want to stay R12, you also have the option of studying for your M609 certification and taking it ($20) so that you can buy R12 (~$20 a pound).
Anyways, for this post, you should donate $25 to my favorite charity.
Fox R134A Conversion