Packard Forum Index » V-8 (1955-56)

As you know, the v-8s have four levers for controlling airflow and heat.

As I understand this system, there are two vents (l&r) which can be opened or closed by the two levers on the left. The two on the right direct the air up (defrost) or down (heat) and the amount of heat.

Am I correct in assuming that the heater is essentially completely independent of/from the fresh air vents?

Put another way, in summer will turning on the heater fan accelerate the flow of air through the vent?

Obviously the back seat heater is irrelevant in this discussion.....

Not really independent. It is in a separate compartment with separate controls but the second air valve on left side which controls the right side air vent has essentially 3 positions. There is a pivoting flapper valve in the middle of the large air tube at the "tee" directly under the heater box. When lever is "off" the flapper is angled one way which positions it to block the air. When in "air" it is straight so air flows past to the passenger vent and when in "heat", the flapper is positioned to block the vent and divert the air up the tee into heater box where it exits the heater/defroster plenum. As you mentioned, that direction is controlled by the lever on the right side. Setting the vent lever between the marked positions adjusts the flow accordingly.

Turning the blower on will increase air into the passenger compartment as long as the lever is in the "air" position. If the flapper is out of adjustment though, even if the lever is in the "air" spot it could position the flapper to restrict to the vent or to allow some flow into the heater box. In that case, if the thermal valve is working properly, heater core should be cold or just barely warm if the temp lever is "off" and it would still come out the plenum or defrost as ambient air.

So if I want defogging in summer I would set the levers (l-r) to air (or off), heat, defrost, cold and that should give fresh air to the windshield?

Yes. That should give a flow to windshield of just regular outside temp air if nothing is blocking slot. Of course that assumes the ducts are in place and flappers and thermal valve adjusted & working properly. Were you able to find or make the missing cardboard elbows?

Depends on a lot of factors such as humidity. U're in Chicago rite there by alot of lakes so i'm guessing it's alot like the Detroit area for high humidity. The best way to defogg or even defrost INSIDE of windows is to turn on air conditioner, winter or summer.

I don;t have any trouble with the 56 Executive. But my 88 Ranger is obnoxious for fogging the windshield in ALL seasons when humitity is high. Even frost in winter on the inside. The heat/defrost will do the job but VERY SLOW. The AC/defrost will clear it about 15 seconds.

This could point to a heater filled with water due to plugged drain vents.

"I don;t have any trouble with the 56 Executive. But my 88 Ranger is obnoxious for fogging the windshield in ALL seasons when humitity is high."

The best way to defogg or even defrost INSIDE of windows is to turn on air conditioner, winter or summer.

You really know how to make it hurt!!!!!!!!! Someday it will be installed and working. Someday. Hopefully while I am still here and functioning.

In answer to the duct question yes, they actually were present but not in place so a smaller friend crawled in and up and somehow took care of them. they are back in their seats and behaving, at least for now.

My more immediate issue is replacing the oil pump and remounting that pesky piece of trim on the "B" pillar for which I can't find the proper tubular speed nuts or a workable substitute. It is hard to imagine a body shop being stopped by this.....

"This could point to a heater filled with water due to plugged drain vents."

That would explain winter fogging. Not summer fogging (severe in 95 degree weather at 80%+ humidity). I don;t run heater at all in summer. The drains are routinely cleaned. in summer the AC will clear the fog in about 5 seconds. Winter about 15 seconds. HEater/defrost in either case of summer or winter is much slower.