heater works for the feets but no dash vents

[z.Leinbach]

Hey guys I got a 90 300zx na and I'm at a loss. My car will blow comfortable air during the day but. When I want heat.. I only get it From the foot vents. Any ideas what the deal is

[NolimitZ32]

your air mix door actuators are likely acting up

[z.Leinbach]

How do I set them straight? Fuse thing or what?

[NolimitZ32]

I'm not 100% on how exactly the system operates but I do know that on the digital control system there are 2 blend doors responsible for the temperature control, either the top motor isn't working at all and has died in the half open or full cold position or you have a physical restriction that is keeping the blend door from opening/closing all the way. What does it do when you set it to cold?

[z.Leinbach]

The defoster vents blow cold and so do the floor vents. I have literally no air from anywhere been the defrost vents (that's always cold)

[NolimitZ32]

OK lets try it like this. List what happens to each vent when you set the AC at diff temps (hot/cold/mild), also is your AC digital control or Analog?

[nexus08]

If heat and cold work, but you just can't change where the air is coming from then your "mode door actuator" is probably burned out. It is a little motor that moves the vent doors when you change the selector from vent to defrost, etc.

Here is a pic of it -



I literally just this weekend fixed mine. It isn't really hard, but getting the part is near impossible as they don't manufacture it anymore.

Your best bet is either a junk yard or finding someone who is parting out a car and willing to pull it for you.

[z.Leinbach]

My ac is. All digital. No matter what temp I set it to. The only part that registers the change is the floor vents. The deforsters and floor vents are always on no matter what

[z.Leinbach]

Update on the issure.. Heat now works from only the middle vents. No more feet vents at least on the driver side, but. All temp ranges all sort of work.