Toyota Repair: Toyota air conditioning, magnetic clutch, toyota camry

Question
I have a  1986  toyota camry.  The air conditoning  doesn't always work.  I  put in a new  a/c switch and that  didn't  help.  When I  turn on the  air conditioning the  switch will  blink  and will not  come on.  Sometimes it  will.  Most of the  time it does this when it  is  hot outside, but  this morning it was cold outside and it would not come on, it only blinks on the  switch which means it is not working. Can you  give me any clues?

Answer
The system may be low on freon, the first step is to check freon pressures and re-charge the system as necessary.
There may be a problem with the compressor or the magnetic clutch, the clutch will not engage if there is insufficient pressure in the system, if everything seems to check out ok, replace the compressor revolution sensor, it's located on the back of the compressor and has two wires coming from it, it is under freon pressure so all the freon has to be removed before removing the sensor.