[Formula51]

My 68' Camaro has factory air and pretty much everything appears to be working as it should. The one exception being that the air vent is always on and the air coming out of it is HOT, like heater or hot engine bay hot!

You don't notice the air or how hot it is until the car is very warm and you feel like you are sitting in an oven!

With all three HVAC sliders all the way to the left and the fan selector all the way up (off) there is no air coming out of the vents AT A STOP. As soon as you start driving hot air starts coming out of the vents!

This is preventing me from enjoying the car so I could really use your guys help.

Where do I look first?

 

[Everett#2390]

In the cowl area, I believe, there is a vacuum actuator to let in outside air.
This actuator is normal open by design. With TEMP in the OFF position, vacuum is applied to close the actuator.

Vacuum source comes from the intake through the firewall to a plug connecting to the vacuum switch on the TEMP control. Then vacuum is routed over to the actuator to close it. Could be a cracked/broken hose or vacuum switch, the plug fell off, TEMP cable misadjusted, actuator diaphram broken. Very common for neoprene hoses to dry rot and/or split at tees and connectors - vacuum leak. A hand vacuum pump comes in very handy for these type of problems. Hose routing is behind glovebox and above heater, of course.

 

[Steptoe]

What everett says above
OR
When the heater was assembled, the 2 flaps where put in in the wrong order....very easy done...I have done that a couple times over the decades.

 

[click]

Here is my cowl a/c dampner... fyi

 

[Formula51]

I have the cowl AC dampner mentioned above and the vacuum line is attached. I checked all the vacuum lines I could find and they were all good.

I could not find a vacuum switch, but I think you guys are on to something with the cable being misadjusted. When I got the car it had a piece of paper folded up and stuck in the top HVAC slot. This paper is necessary to keep the slide lever in the "OFF" position. Without the paper, the slide lever is very easy to move compared to the other two and will slide over into the AC position and the AC would run all the time.

Perhaps the lever is not actually reaching the "OFF" position, but is only going into the "VENT" position. How would I go about adjusting this lever? Do I need to take the dash apart or can I get to it from underneath? Thanks.

 

[Everett#2390]

Vacuum switch is attached to the heater control, top lever, left hand side and can be accessed from the dash underneath - might need a third joint in the arm/hand.

The far end of the cable is adjustable in the clamp. You might have to remove the glovebox, very easy, and work from the dangling door opening. Loosen the clamp, 1/4 inch socket, and slide the cable casing towards the heater control, tighten clamp. Might need to wrap casing with electrical tape for a better clamp grip. Reinstall glovebox only after road testing.

Beg/borrow/steal/cumshaw a hand vacuum pump and attach to outgoing vacuum line and test actuator and road test.

 

[Formula51]

Update. Finally got to pulling out the old CD player (in the glovebox) and found the cable you guys are talking about.

When I move the top lever or should I say let it flop around, it does not move the cable one bit. It appears it is disconnected/broken at the HVAC control unit itself. Does this diagnosis sound correct? If I move the middle HVAC lever, I can see it move the other cable and a nearby black metal lever on top the heater box.

The black metal lever moved by the middle HVAC lever is circled in red in the attachment. The other cable in the picture is the one that does not move.


Looks like the next thing to do is to pull the center of the dash off and slide it out and take a look. Any tips on how to do that? It looks like there are two screws on the bottom corners and thats it....maybe some clips....? I just don't want to break anything.

Thanks,
Eddie

 

[Everett#2390]

The cable at the rear does not move, correct?
Loosen the clamp screw and move the whole cable assembly just to see if the cable is broke or the door it controls is stuck.

Yes, remove the center plate be removing the lower screws and the ashtray bracket, then lift up to unhook the panel from the clip.
Careful, the top clip is plastic and brittle.
Once the panel is off, you will see the screws on either to loosen to remove the HVAC control head.

 

[Steptoe]

Check that the flaps where not put in in the wrong order as my post above...gives the same symtoms....been there done that, and sad to say several times over the yrs lol

 

[Formula51]

I don't understand how to "check" if the flaps were put in wrong? Does my picture describing which flap works (or doesnt work) with each lever explain it?

 

[Steptoe]

can you manually move the flaps and everything works fine?
If the flaps are installed in the wrong order then they hook up on each other and dont open and close the different parts of the heater box and u get hot air instead of cold or visa versa and stuff.

 

[Formula51]

Progress.....kind of.

I took the bracket screw loose at the flapper door and moved the cable by hand and it opened and closed the door. There did not appear to be any obstruction or binding. Check.

Took the center dash apart and what fun that was. The tuner knob for the radio had a washer and capture nut (like what you hold a fender emblem on with) pushed on the shaft to hold the radio bezel in place. When I finally got it off, the radio just fell into the dash. Uh oh, new problem.

The power knob closest to drivers side had the proper threaded outer shaft with a 5/8" nut. I assume the passenger side should have the same thing and I can see the threaded outer shaft down in the radio! What fun. Are those two nuts (around the knob shafts) and tightened up against the radio bezel the only thing that hold the radio in place? It seams like it would bounce around with just those, is there another bracket or something I am missing? It appears the radio was just leaning against the ash tray housing and someone had added some black tape to keep it from bouncing around too much. Don't you just love other people's messes! I might have to start a new topic for this one.

On to the HVAC lever. It appears all the cables are connected. It also appears a stud/rivet/spot weld not sure what you call it has broken lose on that top lever and that is what is allowing it to flop around. See the two red holes in the pic below:

If I line up the holes and stick something through them, the lever still works and appears to get firmer. I did not hook up the flapper door cable bracket to test yet. Does this sound like the problem? If so, any suggestions on what to use to fix it? Maybe I can get a screw to tap into those two pieces....it looks like it would be a real pain to get the HVAC unit out of the dash. Do you have to take it out from the bottom? I can't see how it comes out of the dash since the tabs on the side are behind the main metal part of the dash....

Next thing. From what I can see, all of the electrical connections look hooked up and everything worked (except the vent flapper door) since I have been driving the car. HOWEVER, I found a three spade connection with a black and green wire running to it just haning out up by the HVAC unit:

Any idea what that connection goes to?

Man oh man, it's never simple!

A sincere thanks for all of the help guys.

 

[Everett#2390]

Good work! Why not a 6-32 screw and a locknut on the other side?
You would need to put in a bronze bushing to prevent the pot metal lever from wearing out over time.
Yes, hook up the cable to see/feel the firmness.

Connector could be for the vent not working?

 

[Geezer]

"It also appears a stud/rivet/spot weld not sure what you call it has broken lose on that top lever and that is what is allowing it to flop around."
It looks like the lever is broken in half (Very common) and someone tried to patch it back together, replacements are available in repops. The electrical connector looks like the factory plug for the radio.

 

[Everett#2390]

For OE radio, there should be a strap at the rear pass side corner for support from the brace above radio.

 

[Formula51]

For OE radio, there should be a strap at the rear pass side corner for support from the brace above radio.

Interesting. I did not see that so I might have to make one. Would you happen to have a picture of this?

The electrical connector looks like the factory plug for the radio.

That would make sense since everything worked except the radio. They might have done this on purpose since there are no speakers hooked up to it as they are hooked up to the CD player in the glovebox.

Good work! Why not a 6-32 screw and a locknut on the other side?
You would need to put in a bronze bushing to prevent the pot metal lever from wearing out over time.

It looks like a disaster to try and get the HVAC control unit out of the dash with all the cable, vacuum, and electrical connections. Does it have to come out the bottom of the dash? Any tips?

Ideally I want to come up with something I can use to re-attach that lever without pulling the unit out, but that may not be possible.

 

[Everett#2390]

I have never had the unfortunate opportunity to pull the heater control panel from the dash. I would imagine you would have to start from the bottom of removing everything to get to the controls for removal.

Maybe another member can enlighten you on the procedure.

I have seen a picture of the strap, you might do a search for radio and see what shows up. Basicaly, it is a perforated strap about 1/2 inch wide and attaches to the rear pass corner, whether a stud or existing hole for a short screw, one of the two because an existing case screw would not have been used in the assembly line.

 

[Brandan]

Kind of what Everet said. If you have a console that comes out. The ash tray next, work your way up. The radio and then finally the controller. You have to take off the bezel trim, (four screws from the bottom) then the controller is screwed in from the front and then it should slide out. The controller housing is mostly pot metal and the levers bend and break easily. There might be some picks in the 67 signature that I have linked below. I can't remember if I included picks since I did all that stuff over a year ago. Also there is so much stuff behind the dash with an A/C car that it is easy for a cable to get stuck. The reassembly is just the reverse. It will take youa while to get to the controller. Mine is a 67 and from what I recall the difference is the low blower switch and the vacuum/electric switch. (Can't recall if the 68 had those)

Hope it helps,

brandan

edit: I just looked at my pics and I don't see anything that would help. Let me look and see if I can find one.

 

[Formula51]

I think I have the lever fixed, but it still will not stay in the "OFF" position (Top HVAC lever). There is a plastic plunger that the lever compresses when put in the "OFF" position, which I think is a switch to turn the ACC off. However, that plunger overcomes the lever and kicks it out of the OFF position and turns the AC on.

How do I get the HVAC lever to stay in the OFF position and resist the force of the plastic plunger/switch?

 

[Formula51]

Any thoughts on how to fix this issue guys? I don't want to put everything back together until I get this fixed. Thanks.