Hello!

 

I am still going through my '77 280Z 2+2 and getting this thing and that thing working again. I've noticed that the vents on the car do not seem to be working correctly. I will see if I can explain what I am experiencing:

 

- When I run the vent and have the fan up all the way, I can barely feel the air moving, though I can hear the fan really whirring away. If I put my hand up to the vent, I feel the air, but it's as if the air is not coming from the vent ... but from somewhere else? I am wondering if things are not hooked up properly and or if there is a clog, etc.

 

- If I try to run the defrost/defogger, I hear the fan again (it sounds strong), but no air is getting to the vents on the dash by the windscreen. So, no defogger (which is very bad in the rain!).

 

- This car used to have air, but the compressor, etc., had been removed (this is just FYI).

 

- The heat does not seem to be working. Again, I hear the fan just fine, but feel no heat (see the next point).

 

- When sliding the slider to move from hot to cold, it is stiff and does not want to move at all. I am assuming it is jammed, etc.

 

I plan to pull all this out and have a look, but I've not done this before. Do I need to remove the dash? Or is it sufficient to remove the four screws that hold in the controls to the air/defog/heat, pull that out, and work from there? I just want a little info before I just start pulling stuff out.

 

Any help/advice is much appreciated.

Someone jump in and correct me if I am remembering incorrectly but the 280z vent controls are all driven by vacuum lines that start in the engine bay and run through the firewall. The first thing I would check is the connecting points for all of the small vacuum lines on the passenger side of the engine bay (around the strut tower). The connecting points split, which causes vacuum leaks, and therefore your vent controls fail. This also affects the performance of your engine.

Jonathan, you are indeed correct.  Condition of vacuum lines, vacuum reservoir, check valve for vacuum reservoir are just some of the failure points.

 

To OP. I would download the .pdf of the 77 FSM and study the vacuum routings for the Heater/AC controls carefully. You will find the pertinent section under AC:

 

Link to Nico club with archives of Datsun Service manuals:

 

http://www.nicoclub.com/datsun-service-manuals

 

Direct link to 1977 S30 FSM:

 

http://www.nicoclub.com/FSM/280z/1977/

Pages AC-6 to AC-13 of the FSM show the Vacuum routing and actuator operations. That's a good place to start reading. Good luck.

 

I'm still trying to get my 1976 Vent/Heater/Defrost door working correctly.  Mode door seems to be stuck in Vent or Bi-Level position. Always blows air out of center vents... Which is OK because I only drive the car in Spring and Summer. And I've got the AC working 100%...so it doesn't matter too much about getting heat out of the Foot ducts or Defroster ducts.  I don't drive it in the rain much. 

To get to the Heater Temperature actuator, you will have to remove the Glove box, Heater Motor and then the heater box. Bit of a PITA, but that will give you access to the Heater " kock " if you need it.

 

To get to the slider controls and the Vacuum selector switch you will have to remove the center console. At that point stop and get one of those mechanics mirrors ( I have one with built in LED ) to have a look under the slider control and make sure that all of the hoses are attached to the vacuum switch. Sometimes they fall off.

 

The hoses and connections  are numbered and order is important. S= Source ( from Vacuum Reservoir ), I = Intake Door actuator, then D1 and D2 for two other Vacuum actuators. Numbers are on tiny labels on original hoses and on the bottom side of the switch. They are a PITA to see... that is why you need the Mechanics Mirror.

 

You can of course take the slider controls out.. but it starts to get quite involved.  There are a couple of cables attached to the Slider controls for the Automatic Thermostat control and to the Heater Kock.

Here's a picture of the water kock that gets stiff and makes the cables hard to slide.  I bought one from Nissan for $48 for my 240, it's different though for your car so this part number won't help but it may be close enough to find the right one for the 280, #27116-E4400

 http://www.zcar.com/forum/10-70-83-tech-discussion-forum/122943-78-280z-heater-valve-photo.html

 

Here's the vacuum diagram, post #1

http://www.classiczcars.com/topic/27887-ac-heater-vacuum-control-valve/

a very simple thing to check: there are spiral hoses (like little versions of the hose that comes out of your clothes dryer) that duct the system. they have a foam seal that disintegrates and then they fall off their ports. get your yoga pants on, put your head under the dash upside down and look up on either side of the console and you'll see 'em. mine were both disconnected and just hanging there - an easy fix if you're lucky.

Ha Ha ... I Luv the part about the Yoga pants.

 

Many, many years ago I remember hanging upside down in the Footwell of my 240Z working on the heater box for what seemed like hours. Now I'm lucky if I can change the Spark Plugs on my 280Z with out my back killing me!!

The grease on your vacuum selector valve might be all dried up.  You can rebuild the thing (moderately easy)  Here's how I did mine:

 

http://www.classiczcars.com/topic/32856-refurbishing-the-hvac-vacuum-selector-valve-in-a-1978-280z-useful-info/

 

You also need to check all the vacuum tubes to see that they're still connected and not cracked.  You can easily access everything without yoga pants if you remove the center console.

Thanks Sarah. Nice " How To " on the Vacuum selector switch re-furbish. One more thing to add to the list!!

This is awesome, folks! Thanks a ton! I truly appreciate it!

Dont forget to service/rebuild the vacuum selector solenoids on the pass side fender wall!!