A/C turns on and off by itself. I think it is the power wire but I am not sure. I don't want to tear it apart until I have a good idea. Could it be the alt? Please give me ideas.

 

check the fuse. maybe it blew and the metal is close enough for contact...? that would be my only guess. does it turn on and off while the switch is off or on?

 

I see your car is an 89. I've seen an 89 with digital controls (the controls are not mechanical throw switches but ALL buttons). But I've heard that those are only Canada models... I don't know.

But if your car is digital controls, then you may have a faulty panel. Let's not hope for that.

If your car uses mechanical throw switches then most likely it is the switch that may be having problems not connect or disconnecting.

And like mtcookson... is your AC switch on? Are you using the heater? Maybe not the heater now... but I don't know what the particulars.

Definitely now your alternator though, it has nothing to do with your AC unit.



Good luck

 

If the switch is in the "off" position and the AC is cutting on and off, yes, you do have an electrical problem. However, if the switch in "on," then you could have an over or under charged system.

Like Super32 said, it is not the altenator (should not be).

In an effort to protect the compressor, the system will automatically cut it off if the coolant pressure is too low or too high.

 

What is cutting on and off???? Is it the compressor???? The blower??? Air cold not cold???? Is it that you hear the clicking of the compressor???? Is it the blower switching on and off???? Need more information to help you out.

 

Your engine is different than mine, but there is something I've noticed with the trigger wire for the compressors clutch plates. There is a single wire running to the compressor to energize the clutch plates and on my max that wire rubbs against metal, If your insulation were to rub away then it may energize the compressor. It depends how nissan did the wiring (whether or not the clutch plates are + triggered or - triggered). All you would need to do is put electrical tape over the shorted wire.

 

what turns on and off the compressor or the blower motor. if its the blower motor then check the low - med - hi switch its most likely shot. if its the compressor then check the charging system to see if its charged or even over charged. If the freon (R-12) is fine then the compressor could just be going bad