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Discussion Starter · #1 ·
Hello all,

So, on my 68 when I turn the fan on and move the sector to the defroster, I can hear the fan motor blowing, but I can't feel air coming out of the defroster vents on top of the dash. I'm still figuring out all the little quirks of this car, so it may be that the ducts aren't all hooked up right? Am I missing something obvious? Any ideas? Thanks!
 

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In the pic below you can see the defroster control cable and arm at the very left of the assembly. Make sure that arm moves when you move the defroster control lever. The arm should be in the maximum clockwise position for defrost.

Good luck
Paul

 

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I'm not sure if tour 68 is the same as my 66 but I need the heat and defrost on to have air come out of the dash. The heat selector needs to be open to let the air into the box, then the defrost directs it to the dash. (although mine could be hooked up incorrectly, but it works):laugh:
 

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Is this an AC car? If it is the doors are all vacuum motor actuated. They're easy to test by putting a vacuum on the motor to see if it actually moves the door. If it doesn't that tells you the vacuum actuator is bad, probably a bad diaphragm. The default defroster door position is closed so the vacuum keeps it open.


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In the second post, you can see the flex hose is not even connected to the plenum. There's half your air.
 

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Discussion Starter · #7 ·
In the pic below you can see the defroster control cable and arm at the very left of the assembly. Make sure that arm moves when you move the defroster control lever. The arm should be in the maximum clockwise position for defrost.

Good luck
Paul

After over 40 years, the plastic on the cables gets brittle and tends to break. Check your cables. You may have one with a broken mount which causes the cable to "flop around" instead of moving the flap inside the heater box.
Is this an AC car? If it is the doors are all vacuum motor actuated. They're easy to test by putting a vacuum on the motor to see if it actually moves the door. If it doesn't that tells you the vacuum actuator is bad, probably a bad diaphragm. The default defroster door position is closed so the vacuum keeps it open.


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This is all good stuff you guys. Thanks. My assembly looks a little different than the picture above though?

At one point it appears that it was an AC car, but there's really not much left of it, so perhaps that is part fo the issue? There's nothing to vacuum activate the door?
 

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If your car has the factory A/C unit, it is totally different than the non-air system pictured previously.
There are several vacuum actuators in a factory A/C system. By chance- is the air only coming out the floor plenum? If so, that is indicative of no vacuum to the system.
The shop manual has a pretty good description & trouble shooting section.

Neil Hoppe
 

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Discussion Starter · #10 ·
okay, so, i am getting warm air out of the floor vents, and even a little out of the dash vents. But, the dash vent air feels like it is just overflow from how much is charging out of the bottom vents.

After fiddling with all the heater controls, it seems that two of the three sliders are working. I can adjust the blower speed, and the temperature slider works. However, the heater slider doesnt seem to do anything at all. I can run it through its switches, but nothing changes. Air just keeps coming out of the floor vents. So, I took the heater control unit out and took some pics... does anything look amiss to you? I have no real clue what I'd be taking a picture of, but everything looks like it is where it should be.







At one point I believe this car had AC, it no longer does. Excuse the newbie question, but how would I hook a vacuum up to the motor to see if that might be the problem? Thanks all. I appreciate the patience.
 

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An electric or manual vacuum pump, (eg MityVac) attached directly at the vacuum unit that operates the lever, will prove the actuator, either good or bad.

From there, trace the vacuum line out of the firewall and test it in isolation. The system relies on a solenoid to activate the flow of vacuum through the lies to the lever actuator. Some easy tracing of the electrics and vacuum lines will reveal the fault. solenoid could be faulty. Vacuum lines perished. Wiring bad. Switch unit bad.
 

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