1986 silverado a/c question

[68bowtie]

so i have an 86 silverado c30. a/c no worky. called three shops in town (turlock), all say they don't do R12. i don't know much about a/c systems. i don't know what the problem is with my truck, other than it blows hot air. do you think i should:

a) keep calling shops until someone says yes
b) call them back and ask if shops will convert it to r134a
c) try and self-diagnose and repair the problem (maybe it's easy?)
d) other

i am hoping it just needed a recharge, the truck is in great condition and all parts seem to be intact. i am selling the truck so I'm trying to limit the expenses. if it's gonna be too much headache or cost i may just leave it as-is.