Nissan Repair: a/c, 300zx z32, resistor

Question
i got y1990 300zx,z32 model N/A.ac is working fine but it does not cutting ON and OFF and fan does not cum on.i have checked relays in engine bay its all good,directed tested fan n it run.SO WHAT COULD BE WRONG.i have also change the control unit(second hand)it does the same thing.please help me

Answer
Ifran,

I would check the resistor that controls the blower if that is what you are saying does not come on.  Second, there is a relay that controls the compressor.  Check the relay since you have changed the control unit.  Basically, switch ones of the same model out and see if the problem follows the relay.  But, for the blower it is usually the resistor cluster.  It is located under the dash on the blower case.