Just bought my 69 and the heater works great, but it only blows out to the floor. I'm lost as to what controls this. Is it vacuum? I know there are at least two vacuum lines connected to the back of the dash controls that run through the firewall and connect to a canister mounted on the firewall.
Any advice or suggestions will be greatly appreciated. I don't have a factory service manual yet, so no diagrams available. This is not an a/c car.

 

What series car? Makes a lot of difference in troubleshooting something like this as heater-only big cars and Toronados have vacuum controls, F85/Cutlass have cable controls.

 

Its a cutlass

 

Um, actually an A-body with A/C will have vacuum controls also, which sound like the problem in this case.

 

Odds are the defrost door cable has broken or come loose at either the control end or the door end. Do you feel any resistance when moving the OFF-HEAT-DEFROST lever? Does airflow shut off in OFF?

Defrost door is at the far left end of the heater box behind the dash and the actuator arm is behind the box.

At the control end, the defrost door cable has a BLACK tab on it and connects to the inner hole closest to the pivot on the O-H-D lever. Air valve cable tab is PINK and connects to outboard hole in that lever. Temperature control cable has a WHITE tab and connects to the temperature lever.

Good luck. It's a simple setup, but having the manual and diagrams helps. A lawnmower or small power equipment shop can probably make you up a new cable if needed.

 

Joe, he says it's not an A/C car.

Rocket- does your control have two levers, top one says OFF-HEAT-DEFROST, lower one says COOL-WARM, or does top one have about 6 positions?

 

Sorry, I missed that. I stopped reading after the part about the vacuum hoses coming off the dash controls.

 

Vacuum lines threw me too, is why I've asked about his control head. Only other vacuum operated accessory that could be inside a non-A/C car would be vacuum trunk release or possibly power door locks, which would also have the firewall vacuum can. Both of those would be unusual on a non-air car though.

Wondering if it's had something changed out over the years.

 

I opt for the broken cable at the heater box end... I fixed Muskrat's with a hot glue gun

 

Well actually, it looks like it was originally an a/c car, because it has all of the controls on the panel for a/c. However the car was a drag car in its past life, and im guessing thats when the a/c got ditched.

 

Ah-HAH! Now we can diagnose yer ailment!

Simplest thing to check- there should be a vacuum line from the vacuum ball on the firewall to a vacuum fitting on the intake manifold. Without it, no vacuum and system will default to floor position.

The other vacuum line from the ball goes thru the firewall to the control head.

There is a black/white stripe vacuum line that goes from the control to the hot water valve at back of the intake manifold.

These are the three that cause the most grief with HVAC vacuum problems.

If one of these isn't the problem, we'll dig deeper. The 69 manual isn't the clearest on vacuum line routing and diaphram locations and it's best to have it in front of you if there's problems with the heater box itself.

 

Well that probably just solved my problem. The car has an edelbock performer rpm manifold on it, and im thinking that maybe it doesn't have the vacuum port on the back?

 

Most Performers I've seen have a threaded bung somewhere on the manifold for this vacuum fitting.

If not, find a manifold vacuum fitting on the carb and run a vacuum hose from it to the vacuum ball and see if things start working. If it's an automatic trans car find the modulator vacuum line and tap into it.

 

Okay thanks.

 

I appreciate everyones' expert advice and I've tried to look at what was suggested. I'm attaching pictures of the vacuum can on the firewall. I see two vacuum posts, each with a line heading back through the firewall. I am really lost and look forward to more help.

Thanks.