Toyota Repair: air conditioner cooler switch, air button, freon

Question
i recently inherited a 1993 4 runner with a brand new engine and trans. with the air button engaged, sometimes it works, sometimes not. i had the system charged and when it does work it is very cold. the light on the switch is on but blows hot air.  very sporadic on and off.  i know the system is charged, and the switch light is on.  could it be the cooler switch? how hard is that to change?

Answer
The problem is not the switch, there are many things that could be the cause so I would recommend having a certified a/c technician look at this, the first thing would be to connect pressure gauges to get a reading of the freon pressures on both the low and high pressure circuits.