Ventilation

[Blue124]

I have a 1978 and no owner's manual. I have two questions please!

1 - Does this car have fresh air vents under the dash? If so, where are they and how do you open them?

2 - What is the correct position for the heater/defroster controls for everything to be OFF? Right now I have them down, down, down which seems to be the best position to stop the hot air but I still get some hot air.

Thanks!!!

[beachboy]

Up, down and up, is what you want.
Makes no sense, but you want heat, heat and defrost. I dont think that 78 had fresh air vents

[zachmac]

First, search under heater controls and you'll find lots of posts on this.

The best piece of information is how to interpret the little colored arrows. They are NOT what you think, NOT arrows. Basically they indicate low (or no) flow to full flow with the pointy end of the arrow being minimum and the wide part being maximum.

From the driver's side working left:

First control open or closes a single air inlet under the cowl at the back of the hood. If closed it means there is basically no (or little) flow of air through the heater / air box. As per the above discussion, down is toward the pointy end of the blue triangle meaning minimum air flow; vent closed.

Next is the "heat" control. It opens and shuts the valve that allows hot water from the engine to pass through the heater core inside the heater / air box. Up is toward the little end of the triangle and corresponds to the valve closed, minimum or no hot water through the core and minimum heat. Down is the direction of the wide part of the red triangle; valve full open and maximum heat.

Finally you have heat versus defrost control. This lever open and closes a large flapper on the bottom of the air box. When it is on heat (down) it has the flapper open and most of the air flow is directed toward your feet. When it is up, the flapper is closed forcing the airflow up a plenum in the box to the air vents on the dash. The air will be hot or cold depending on the position of the second lever and even with it down (flapper full open) there will still be some air flow out the dash vents.

It is important to understand tow key points:

All air flow is in from the cowl flapper, through the air box and out. If the flap is closed (first lever full down) there will be very little air flow regardless of fan speed. You are trying to pull air through the bow with no inlet!

Second, heat or not is totally a function of the second knob that controls the hot water valve. If it is closed, you get outside air temperature air (provided the flapper is open). if it is open you get outside air passing over a hot heater core and then out (to your feet or the dash, depending on the third knob position).

[zachmac]

BTW, you can download a manual here: http://www.fiatspider.com/f08/viewtopic.php?f=18&t=6462

[Blue124]

Thanks very much! I'll make the adjustments to the heater controls and hope to get some fresh (cool) air instead of the heat.

And thanks for the link to the manuals!

[courtenay]

Great explanation, Jeff. Those little arrow thingys have baffled me from day one. Any time I've had heat or defrost in the car it's been more by accident than desigh! Thanks!

[SLOSpider]

I thought the 78 still had the manual rods under the dash on each side to let fresh air in. I like that feature.

[zachmac]

I thought the 78 still had the manual rods under the dash on each side to let fresh air in. I like that feature.

This may well be? I only have my 80 for a reference.

[Redline]

They are rather infuriating controls, but at least you get to feel like a pilot controlling a multi-engine plane! And in contrast to a late-70s or early-80s Porsche 911, you can mess around as much as you want with the heater controls between the seats and run no risk of a very expensive mistake!

My Coupe has a nasty habit of permeating the cabin with the tang of hydrocarbons. I'm thinking of relabeling the left slider "Asphyxiation Control".

[zachmac]

My Coupe has a nasty habit of permeating the cabin with the tang of hydrocarbons. I'm thinking of relabeling the left slider "Asphyxiation Control".

Unfortunately the location of the air intake makes it a perfect point to pull air coming out of the rear opening hood. If you have fumes in the engine bay there is a good chance you'll have them in the passenger compartment with the air inlet open. A tight rear hood seal helps IF you can get your latch adjusted to hold the hood down tight.