'93 Ford F-150 A/C

My A/C isn't as 'cold' as it used to be. I'm guessing I'm low on freon. Do they even make/sell freon anymore? Will I have to change over to R132a? If so, has anyone out there done a conversion and can you provide info on what's involved?
Thanks

Correction: My question should have referenced R-134a and not R132a

Nope can't get freon anywhere that I know of...I changed mine about two years ago on my 99 F150....I just let the last of the freon out (found out after I did it that I should not have left it hiss out into the air) and bought the refill kit for the R134a and filled it back up. No problems since.