when i hit the switch, i hear a click, but no air comes out. when it is in on position and i kill the engine, it makes a long quite sigh. it used to work great, then only sometimes, now never. i know nothing about air conditioners, so any help is greatly appreciated. thanks! oh ya. its an 86 4runner SR5 turbo.

 

Does it blow heat and room temp air, but just not A/C or is the fan not even coming on?

 

could be out of refrigerant. low pressure control prevents compresser clutch from engageing.