AC Only Comming Out Defrost Vents

[islandtuner242]

Ok i've got a 1990 n/a that's only blowing out of the defrost vents and no other ones can anybody help?? BTW it has the auo climate control feature (Bunch Of Crap!!!!!)

[Ace2cool]

Unfortunately, the '90 didn't have selectable vents. Nissan figured that they knew the best way to heat/cool a car efficiently with a current temp/ desired temp combo. They quickly realized that this setup was absolute garbage and canned it for a selectable vent controller.

What does it do when you change the temp on the controller? It should change vents if you go colder, if trying to use heat, or vice-versa. Will it change vents at all?

You could also try the CC dignostics. I never quite understood it, but you might have some luck:
http://www.ttzd.com/tech/autocc/autocc.html

And lastly, are you trying to use heat or cooling? I know your post says A/C, but a lot of people use A/C as a descriptor for both heat and cooling. If you're attempting to use heat and the car's heater core hasn't fully warmed up yet, it will only blow from the defroster and very slightly from the legwells. Once the heater core has warmed up, it will change vents to more efficiently heat the car.

[AchilleZ32]

This started happening to me last Friday. I shall read through that giberish Aaron. i'll let you know if I figure anything out man.

[marty1mc]

Does it switch to the floor when heat is put on or to the windshield when you select defrost? If not, then your mode door motor is probably the issue. It's not bad to replace, but finding one is an issue. Nissan no longer has them available. Even when they did, it was pretty expensive ($150). But, you may be able to find one used. It attaches to the heater box on the left side by the gas pedal and controls where the air flows when each function is selected.

[DankZX]

And while you hae the dash out you might as well replace anything else that could potentially break. I had to replace the heater core and the actuator at the same time so that was nice but its still kind of a pain. There are some good write ups out there if your wanting to take the dash out to do it.

[marty1mc]

The mode door motor doesn't require a dash pull. It's mounted on the side of the heater box, not under it like the air mix door motors. Those are a royal pain to get out...

[AchilleZ32]

Does it switch to the floor when heat is put on or to the windshield when you select defrost? If not, then your mode door motor is probably the issue. It's not bad to replace, but finding one is an issue. Nissan no longer has them available. Even when they did, it was pretty expensive ($150). But, you may be able to find one used. It attaches to the heater box on the left side by the gas pedal and controls where the air flows when each function is selected.

What a bummer. I'll start looking for one, as I couldn't get it to switch the floor in diagnostics mode either. Thanks Marty

[Ace2cool]

Gaige, I might be able to find you one. I have a few parts guys when it comes to the Z32. Lemme give my parts guy a call tomorrow, and I'll let you know. Your phone back on yet?

[AchilleZ32]

Yeah, phone's back on If you can't find one, no big deal. My uncles best friend restores Z's and has about 3 300's for parts in storage. So, im sure i'd be able to get one that way. I have to go to his house anyway to get my TT sway bars.