please help i only have air blowing out of the defrost vents!!!!

[eliminator024]

i have a 1990 Nissan 240sx it only blows air out of defrost no where else and i cant stand this California summer heat lol, can someone please help me out on how to fix the problem. Also the light to the a/c button does not come on i dont know if it works or not or has anything to do with the problem.

[jesse_s13]

Have you checked to see if the ac compressor turns on?

[lazysk8er2]

check the fuses!

[AutechKouki]

Defrost vent might be air vent servo motor being out, and your compressor not turning on is most likely low refrigerant charge or no refrigerant at all.

[eliminator024]

Its not the fuses or the compressor its something else causing it to only blow from the defrost vents, checked the fuses there fine. I was using the heater last year and all of the sudden it only blew through the defrost only so idk what broke.

[mad-ass]

your hvac unit maybe dead is no longer telling the vent arms to move to correction position when position selector is pressed.

[eliminator024]

So I need a new control unit the conrtol part by my radio and it should work??

[mushmonster]

With a test light check power at the mode door servo (driver side-right of gas pedal) when actuating each mode if no power, may be control head or power from 10A fuse at drivers side kick panel. No ac light may mean issue at the relay(drivers side engine comp fuse block), wiring, or control head. check for power at ac clutch on compressor.

[jaked23]

the air ven doors are ran by vacuum. you probably have a vacuum leak somewhere. when there is a vacuum leak, it defaults to defrost

[eliminator024]

Where are the vacuum lines under the dash?