1966 Chrysler dash vents doing something odd...

[TylerW]

Hey there:

I've been driving my '66 with standard heater/AC later into the year and had to use the heater a few times. Something isn't quite right. The air temperatures out of the 2 center vents above the ash tray are distinctly different from one another. The air out of the left(driver side) vent is warm, and the air out of the right vent is cool. I didn't think to check the far outer passenger vent but I would suspect it's also producing cool air as well.

This is happening with the "heat" button selected. I'm not familiar enough with it to know whether there is even supposed to be air flow out of the dash when the Heat button is selected. I read through the FSM but it wasn't overly helpful. The AC is discharged and non-op, so it is not operating and having an influence over air temperatures.

Anybody have this happen or know why it might be? Thanks.

 

[Gerald Morris]

The heater is actually controlled by engine vacuum. Look down, by the firewall, over the transmission tunnel and you will see a large vacuum diaphragm attached to the heater box by a rod. THIS ROD cranks open or closed a vane inside the heater box which directs air to either the defrost vents up top, or the heater vents. Since your ride has what looks like from your description, one with factory AC, I guess 2 central vents are attached to the heater box. Check the TOP lever too. This one attaches via a cable to a vane over by the glove compartment. The lever there opens or closes air flow from outside. When closed, it recirculates air inside, warming it more rapidly. It MIGHT be stuck open.

Finally, the buttons control a vacuum switch, which controls one or 2 diaphragms, as the one aforementioned. If you REALLY NEED HEAT, you CAN disconnect the diaphragm completely from the control rod and then manually set it where you want it. If cranked all the way over one way, it will blow through the defrost vents. Turn it just BEFORE THAT setting for maximum heat. The fan will blow hard, and you will get plenty hot air from all the lower vents on the heater.

 

[CBODY67]

When the "HEAT" button is depressed, there should be NO air coming out the dash vents, ONLY the floor vent located over the trans hump. Only with the "Cool" or "Fr Cool" (inside air and outside air, respectively) will result in air flow from the dash vents.

Download the FSM from www.mymopar.com to get a map of the hvac system's vacuum lines and such.

Let us know what you discover,
CBODY67

 

[Gerald Morris]

When the "HEAT" button is depressed, there should be NO air coming out the dash vents, ONLY the floor vent located over the trans hump. Only with the "Cool" or "Fr Cool" (inside air and outside air, respectively) will result in air flow from the dash vents.

Download the FSM from www.mymopar.com to get a map of the hvac system's vacuum lines and such.

Let us know what you discover,
CBODY67

That makes sense. Not having a factory AC, I didn't know for sure. The FSM helps some with this stuff. I know that my heater comes out from those bottom vents. (I think there are two, one on each side of the hump.) Interesting how they circuited the blower motor to run full speed only when the "Max" button is pushed AND to open the internal gate fully for hot air from the core. I very seldom use this thing down here, but am glad I got it going. The vac switch is reparable, if I ever see need for it. That was the ONLY vacuum device on this car when I got her, which I liked quite a bit.