Hello all...I just bought the daughter a 93 240 sedan yesterday....I take it to activate the a/c it's the blue rocker with the snow flake on it (no manual or repair book yet) and the blower switch controls the air flow....well if so, with the switch turned on, the blue light doesn't light and the clutch doesn't engage but the blower blows hot air...okay the fuse is good, so where should I check next, bad switch?

 

Do you have a small **** near A/C switch? If you do that is the adjustable termostat, turn on clockwise.
If no **** then check under hood at rear of compressor for suction and discharge schrader valves. The head of them look just like a tire valve. Using anything i.e. air guage,tip of something, depress valve tip(engine off ) quickly, if system is charged some pressure should escape.
You could be lucky enough and the system could have been converted to R134 and you my have a fill valve top side some where in line on hose.
If you find pressure on system then it my be to low to trip low pressure switch. Next step find the a/c/ dryer you should see the switch screwed into it. Disconnect the plug and jump across the plug end terminals. If compressor engages the system is low and needs topping off. If that is the case then you can add freon(R134) yourself with a kit that comes with a built in pressure guage to help you add prper amount. If system is still R12 then its a trip to a certified A/C guru for evac and conversion to R134. remembner a new dryer is recomended any time system is opened or lots of miles. Rule of thumb is if system cools good in early morning or late in day, but as ambient temp rises during day and cooling falls off....replace dryer.