In Praise of: Detroit's HVAC Engineering
With all that the domestic automakers have done wrong, it’s important to remember the things they’ve done– and continue to do– well. In his post about dumb moves behind the wheel, Jonny Lieberman highlighted one of these engineering accomplishments: Heating Ventilation and Air Conditioning (HAVC). As JL pointed out, even when Detroit was making malaise-era cars that barely ran, their HVAC systems were the “envy of the world.” Sure, Volvos and Saabs had good interior heating and defrosting systems, not to mention heated seats. But Detroit led the world in keeping drivers physically comfortable. In this, geographic happenstance played a critical role.
In European cities, streets are narrow and go in all directions. The history and glamor of road racing looms large. Small cars, precise handling and confident cornering were always high priorities. In contrast, Detroit’s streets are broad and, for the most part, adhere to a 90 degree grid. Boulevard and interstate cruising defined the automotive gestalt. Motown’s suspensions were calibrated more for comfort than precision handling. And HVAC systems enjoyed pride of place.
Every year when the NAIAS rolls around, people question the wisdom of holding a big auto show in Detroit in January. The weather outside the hall isn’t Fargo or International Falls cold, but it’s enough to evoke mention of brass monkeys’ testicles witches’ mammaries. Statistically speaking, January’s average temperature: 17.8°F. Not to mention wind chill; the “breeze” coming off Lake St. Clair can cut you to the quick. And yes, there’s snow. Average annual snowfall: 41 inches.
Detroit auto execs and their contemporary counterparts may have never experienced the joys of dealer service managers and warranty work but they still had to deal with Michigan weather on the way to and from work. Auto execs don’t like to be cold. Neither do engineers. Working together, they made sure that Motown’s products could warm their bones– and keep them warm– through the worst of the midwestern winter.
Quick digression…
I reckon the Volkswagen Beetle’s token HVAC system is one of the main reasons Motown diss-missed the small car boat. In January, Wolfsburg’s average temperature is a relatively balmy 38°F. This may account for the fact that the Bug’s heating system didn’t have an electric blower. Pressurized air was ducted off of the cooling shroud into the headers/heat exchangers. Heat, then, was speed sensitive– under the best of circumstances.
After a Michigan winter or two, with plenty of road salt rotting the German car’s undercarriage, the Vee Dub’s heat exchangers and heat ducts were perforated with rust. Small wonder VW offered a gas heater: a self-contained 18k btu gasoline-fired furnace.
Back to Detroit, which isn’t located in a desert. Still, the average July temperature clocks in at 83.4°F (Wolfsburg 72°F), with plenty of relative humidity to keep the sweat flowing.
Air conditioning was originally introduced by Packard in 1939 as a $274 option. It filled up the vehicle’s entire trunk. To turn it off, the driver had to stop the car, turn off the engine, open the hood and disconnect a belt connected to the air conditioning compressor. In 1941, Cadillac built 300 equally inconvenient air-conditioned cars.
GM’s Harrison Radiator Division developed the first efficient, affordable automotive A/C unit. Offered as an option on all 1955 V-8 Pontiacs, it featured a two-cylinder reciprocating compressor and an all-brazed condenser. Fitted with a magnetic clutch, the unit didn’t need extra power to drive the compressor, which greatly improved performance and fuel economy.
Meanwhile and anyway, by the 1960s, domestic automakers were improving ventilation systems. Cars had air vents in the fender wells, with cable actuators on the kick panel. Flow-through ventilation was soon integrated into the heating system. By the 70’s, automotive air conditioning became a factory option on Detroit’s popularly priced cars.
Upgraded HVAC systems were an excellent way for dealers to add to a car’s bottom line. (Heaters were an extra cost option well into the 60’s.) Many of our Best and Brightest who grew up sweltering in cars without a chiller gladly paid for extra for A/C when they could afford it.
Another digression…
My dad, may he rest in peace, loved air conditioning. American Motors used to label the maximum A/C setting “Desert Cool.” They must have had my dad in mind. Though he liked his options, as far as A/C was concerned, they could have had a single setting: max cool, max fan. In the 1970s, he switched from Oldsmobiles to Mercurys; you could have cooled your drink on the dashboard of his 1974 Grand Marquis.
Thirty-eight years later and I’ve never driven a Detroit product that couldn’t blast full heat in subzero weather, or keep you comfortable on a blistering hot summer day. Just about every automaker in the world now makes fairly sophisticated climate control systems. But it’s a clear case of meeting a high standard that Detroit, to its credit, has set.
Ronnie Schreiber edits Cars In Depth, the original 3D car site.
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GM has done a good job over the years on HVAC: I well remember our 50 - 60's series Pontiac AC's doing a great job heating or cooling those long trips. They were also good at sending hot air to floor and defroster, and cool air to upper level vents. However, recent GM models make it difficult to keep the AC off during demist or defog, resulting in less fogging but longer times to deice a windshield. Japanese cars, all seemingly relying on Nippondenso systems, tend to pour air out the side vents irregardless of HVAC upper/lower air setting. In the cheaper cars, that air's unheated, forcing you to manage air vents as well as heater controls. Higher-end cars add electro/pneumatic valves for control those ducts by HVAC controls.
My R-12 cars all cooled very well no matter who made them. My '81 Moostang with the 200 c.i. six with 90 whole HP used about 10 of it to turn the big Tecumseh piston compressor. It cooled but was expensive to provide gas for. Made a thrumming noise that could be heard throughout the car. Nothing was wrong. Just a gentle change to the sound of the car. My '84 and '97 VW convertibles (Rabbit & Cabrio) both make ice cubes in the summer. Very cold. VERY good heater too. The '97 Cabrio has a variable displacement compressor so there is not any cycling of the compressor making for a nice refinement. My aircooled Beetles made VERY good heat if the system was intact. Yes, it was rpm dependent but it was enough at all speeds to roast my sneakers. The problem was that the flappers leaked a little in the summer so I had heat then too. The flappers were a little TOO low tech in that regard. My aircooled '78 VW Westfalia van has never made any really hot heat and the fan never moved enough air to be really useful. Remember keeping it all intact? The U-tubes int he exhaust had a thin 2nd layer of sheetmetal that insulated the pipes but exposed to any weather or salt they disappeared quick. That was the key to keeping the heat really hot b/c the system just wasn't designed to deliver any real volume. I suspect too much volume and the heat temps (and engine temps) begin to fall. I drove my friend's '78 VW Rivera camper with all the same van bits and her pipes are intact (or were) and the van heated very well. Enough that on a freezing night cruising around town my wife asked me to turn the heat down. I too like all of the old methods for cooling the car without a/c. Cowl vents, vent windows, etc. Prob lost to the cost cutters and to the folks tasked with cutting wind noise. Our aircooled VWs do a pretty good job of keeping us cool without a/c. I lived in Italy in the early 90s and alot of Italian people I knew just didn't see the point to having a/c when gas was $5 per gallon (and our gas was under a dollar). We also got used to the heat and the transistion from the cool car to the hot weather really was a shock compared to just enjoying the open windows breeze. Those good people also take siestas and thus try not to be out in their cars during mid-day heat. Finally alot of people were still driving 1L and 1.2L cars and really didn't have alot of HP to spare to a compressor large enough to be effective at cooling a hot car. Most of my Italian friends welcomed my '84 VW Rabbit's a/c but had no taste for artic temps when they would have to step out into 95 degree heat in a short time. Everything in moderation. Cool but not cold in the summer, warm not hot in the winter was how they heated/cooled their lives. I've got to say you can get used to it. I went without a/c this past summer in the Cabrio intentionally ($4 gas - remember?) and it isn't bad. I didn't put the top down when the sun was out though - just roasts me when it is July hot and the sun is bright.