A/C Question on 68 c10

[socalkevin68]

Go my A/c charged up...new hoses..and works great..well it did for a day..now it still blows ice cold..but just on lowand medium speed...
My A/C system is all stock 1968..with the R12 in it..
My question is...Does the High Speed on the Fan Switch have a separate resistor?
I looked up some a/c parts in my Classic Parts Catalog and I see a A/C Blower Motor Relay and a Heater A/C blower speed resisitor..could either one of these cause hi speed to go out?
I asked the guy who did my a/c for me and I t hink he wants me to bring it in for him to fix for more money..and to be quite honest i'm beginning to be tapped money wise....i'd like to fix myself if i can...Any help would be appreciated here..
thx
kevin