Great moments in Saab design – Saab 900 HVAC system

How many of you can remember getting into a Saab 900 for the very first time, seeing a bunch of dials and arrows on the dashboard and thinking “what the heck is that???” That was certainly part of my first Saab 900 experience.
The Saab 900 heating, ventilation and air conditioning system is quite likely to be one of the first things that many former 900 owners will remember about their cars. It’s very Swedish, very Saab and very, very good at its job.
The dials were made chunky enough so that they could be operated easily even if the driver was wearing gloves or mittens (though mittens and cars don’t go together that well, IMHO). All controls were within easy reach of both driver and passenger and are easy to operate with covered hands.
Going from the left, the first two dials are pretty self explanatory, being fan speed and temperature. The uninitiated may wonder why the fan only has settings of 1, 2 and 3. How do you turn it off?
The answer to that question and the beauty of the Saab 900 HVAC system lies within the third dial, which controls the vacuum driven ventilation system.
Saab’s thinking was that if any of the vents are open, the system is operating. Therefore, the fan should be on. The ventilation dial therefore has a ‘0’ position at the bottom, which is where the entire system shuts off. Move the dial from the ‘0’ position and the required vents open up and the fan operates at the speed indicated on the fan control dial.
The ventilation dial looks quite complex at first glance, but is actually simplicity itself.
From a cold start, the ventilation dial should be turned 180 degrees to point at the top position, directing air at the windscreen. Shortly thereafter, the screen should be sufficiently clear to move the dial into the next position (arrows up and down) where equal amounts of warm air are directed at the windscreen and at the occupants’ feet.
The down arrow is for warm air at the feet only (though a small amount is still directed to the windows)
Saab900HVACvents.jpg The down arrow with the box at the top is many a C900 owner’s favourite. This directs warm air at the occupants’ feet to keep them warm at their core, and directs cool air through the center vents to keep the occupants fresh and attentive. A perfect combination!
The small arrow pointing left and right is for cold air. It will be directed through the side vents at the speed indicated on the fan speed selector.
The large arrow pointing left and right directs cold air through the same vents at maximum speed.
The final position is the ‘0’ position to turn the system off.
A few fun facts.
* At full force, the Saab 900 HVAC system is capable of pumping out 100 litres of air per second!
* At a temperature of -20F and with the car running at idle, the Saab 900 HVAC system was designed to have the cabin temperature at +70F within five minutes.
* There are 12 air vents in the Saab 900, all of which were wind tunnel tested for best airflow and evacuation.
* Saab had a world first when they introduced a pollen filter for their ventilation systems in 1978. It’s an electrostatic unit that filters out anything over 0.004mm in size from incoming air.

Images and info from 1986 Saab 900 engineering brochure on Wulf’s SaabMedia website.

4 years 4 months ago

Excellent, this is why I love Saabs. Makes me wants to go for a ride in my C900 and try the down arrow with a square (which I never tried).