Nissan Repair: aircondition, nissan 300z, pressure switch

Question
I have a 95 nissan 300z. when i am at idle the a/c blows hot when i am at between 5 and 70 the a/c blows cold. at 75 or over the a/c will blow hot then i drop it back down to 65 or 70 it blows cold again. Any ideas what the problem could be. Thanks  

Answer
I would think the compressor cut out switch is turning the compressor off.  Or, the pressure switch on the system is over pressurizing and turning the compressor off.  I would think the computer is cutting off the compressor.  You should be able to feel if the compressor cuts out when the system gets warm.  If it is then you need to check the pressure of the system to make sure that it is not overcharged.  If it is this can cause your problem.