luvatenor

Hi, just purchased a beautiful 1984 300zx, which has some quirks I must attend to. When I move the air to 'face' and temp to cold(left), no outside air comes out of the vents(the floor vent does work). Any suggestions?-Here is a pic of the car:

Donn144

Darn sweet..how many miles on it?

luvatenor

It has 54,000 original miles(autocheck and carfax verified )-In the womans garage for 15 years untouched-seller put in a new timing belt, water pump, exhaust, shocks, oil change, new injectors and factory maintenance- all for $4400.00-very pleased-and fast!!

zxguy1986

Congrats on a great Z!

Your air distrib system works off of your vacuum hoses/lines. If they are old and/or leaking or missing, your system ignores your commands. May as well begin your work at the hoses themselves. Inspect and replace as required. You can use your FSM or thumper's great post: Vacuum Lines Note that it's a single vacuum system with all those hose connections, exposed and concealed - so any weak link in it screws up the whole system. New hose is available at good parts stores.

Be sure to use only the correct inside diameters to keep pressures up where they should be. Once your hoses are set - and it still doesn't work, check the vacuum pump(s)' output(s). Replace if required. Pumps were originally not very strong anyway so any fall off in performance makes a big diff. The big one is black and sits behind your right headlight.

If it still doesn't work, you need to take the dash apart enough to examine the links from on-dash switches/levers to dampers behind. Some of them are housed and hard to get to. Clean damper paths and lubricate hinges. Note that vacuum hoses are also back there and may have degraded or disconnected over the years. Probably they are all original so replace them.

If your electrical connections are all good, system should work as intended.

PredatorZ

Under the steering column, in the panel below is a little vacuum switch, flip it back and forth and see if that makes a difference, it has something to do with fresh air vent, but on my 84 no AC if I had it in wrong position. if you end up needing any parts I totaled an 84 with about 90K on it a lot of the parts are in great condition.

luvatenor

Thanks for the info-I looked under the steering column but did not see a switch-actually a lever which goes up and down-Do you happen to have a pic of this switch-thanks-Rolf

zxguy1986

It's on page HA-5 of your manual. Called vacuum switch, middle right of page. Just flip it up and down a few times, then leave it down. See if your distrib system changes its mind...

luvatenor

[QUOTE=zxguy1986;334463]It's on page HA-5 of your manual. Called vacuum switch, middle right of page. Just flip it up and down a few times, then leave it down. See if your distrib system changes its mind...[/QUOTE
]Thanks for your response-good thing I have the factory manual-right now(I looked) the lever is somewhere in the middle-I'll try it tomorrow-doesn't go out in the rain-Rolf

zxguy1986

OK, remember to do the flipping with the air blower on full. If you have weak vacuum pressures, the flow can add the push you need to move your dampers. If this doesn't work, you need to start inspecting/replacing hoses, etc.

Your Z is worth it. She will run perfectly but she's looking for some reassurance that you really care about her... Sounds like she has some doubts about you now... Don't do that. She's sensitive...

luvatenor

Hi, I followed the procedure you provided me with(thank you)- I now have fresh air coming from the defroster vents and some air from the left face vent. Still no air from the center or right face vents(face air button depressed(2nd from left). If indeed it is the vacuum hoses that are suspect-what do I look for with the hoses(swelling, splits, ect). Again your knowledgeable advice is more than welcome-Rolf

zxguy1986

Any original hoses will have splits and cracks in them, some very small and hard to see. Some will be split where they stretched to fit their respective metal tubes. I would replace all of them. Easy enough to do until you get under the dash... but worth the time and labor.

Do them one at a time. Pull off one end of the old hose, cut the stretched part off, match the inside diameter, put the new hose on there, follow the hose to the other end, remove it and attach the new one, cutting the new one to the correct length. For hoses that run inside the wall of the engine compartment, tape the new hose to the end of the old one and pull the old one through and out, threading the new one as you go.

Re-use the old hose clamps or get new ones. You need clamps where there is a chance that the hose will vibrate off the metal tube or where you need a tight fit. Don't over-tighten the clamps or you can cause a split. As you work, check your FSM or thumper's diags to see if each hose is where it should be. Thumper color codes hoses by inside diameter, I think. Diameter needs to be right to keep system balanced. Previous owners have had 30 years to disconnect hoses and leave them off or put them back in the wrong place, or install the wrong diameter, etc. You get to fix that. When you are finished, use a plastic strip-tie to bind adjacent hoses together, keep them from flopping around.

Inside and under the dash, hoses are hard to get to but have to be replaced. While you have the dash apart, inspect and clean the dampers you can see. With the dash open, see if you can hook up your control switches and test that everything is working. Even if you don't take out the main heating/cooling console box, you can probably open it to clean it out. Dust and crap on the exchange units that air flows through. Also a good time to disconnect, clean and reconnect any electrical/harness connections you find. Rogerz uses separate spray cleaner and corrosion-preventer. Check his posts for the names.

That should do it. Nice to have the system working like new! She purrs...