scrofcheck

A/C I have a 92 G20 series van with a new A/C unit. Problem is it only blows cold air in normal position. When I switch it to Max nothing comes out. Mechanic said I need to replace the cluster that controls the A/C and heater. I forget the correct name for the part, It's on the dash heater switch , temp etc ?? Claims vacuum switch on back side is probably bad. Wants $ 150.00 for a used one and $ 100 labor Ouch. Does this sound right ?? Thanks
BTW what is the correct name for that part ??