Volvo Repair: air conditioning, r 134a, volvo 850

Question
I have a '94 volvo 850 turbo, and just recently I noticed the air conditioning not working. Air blows out but It doesnt get cold. and when I turn the A/C on the RPM dial kinda goes up a bit when I am Idle-- could you tell me whats wrong, and if it is the freon do you know what type it is? Thanks  

Answer
Hello Jade,  The most likly cause of a/c leaks in the 850 is the 'evaporator core'. Its located behind the center of the dashboard.We started seeing this at about70-85k miles.The freon is R-134A .The idle is programed to rise when a/c is requested.If you find the comp.comes On and Off in 3/5 seconds intervals,the freon level is low,but just high enough to activate.Have the system evacuated(emptied by vacuum to negetive pressure) and re-charged with 'dye' and have her re-checked after 1 wk. or sooner if it stops cooling.The dye leaves a trail that is seen with an ultra violet lamp.The diag.recharge will run $30/$60.Thank you and good hunting!  PKD