Auto Q & A
Auto Q & A
By: Dr. Wheels
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Posted by editor Fri Jul 28, 2006 16:37:25 PDT
Viewed 817 times
0 responses 0 comments BQ Auto -16
Auto Q & A
Dear Q & A: My son just bought a new Saturn Ion. It has air conditioning, but when he took me to lunch the other day in sweltering weather, I asked him why we were riding with the windows open and experiencing the heat and road noise instead of using the air conditioning. He said he was doing it to save gas. Is that a sensible thing to do?
— Mom Cyn
Dear Mom: Turning that compressor pulley under the hood to operate the air conditioner does require some engine power, as your son evidently believes. But the added draw of modern auto A/C systems is so small, fuel economy-wise, that he could easily compensate for it, and more, by driving a little more carefully to save fuel on start-ups from stoplights, and exerting easier pressure generally on the gas pedal while the air is on.
Turning off the air conditioning to save significant amounts of gasoline is one of those old tales that have survived from the early days of automotive A/C, when big, high-draw systems did cost drivers 5 to 10 percent more gas to be cool while driving. His Ion, with fuel economy ratings of about 25 mpg city, 32 highway is so fuel-stingy to begin with, there are more comfortable ways to save a few pennies during miserably hot weather than driving with the air off. Incidentally, Mom, your son chose one of the safer small cars. The Ion has a five (best) front impact NHTSA crashworthiness rating, and a four rating for side impacts.
Dear Q & A: We travel the Grapevine mountain route to Los Angeles quite a bit and my husband always shuts off the air conditioner in his 2005 Toyota Matrix on the uphill part of the highway, apparently obeying the signs that warn “turn off your air conditioner for the next (xx) miles” or something like that. Is this necessary, or are these signs left over from the days of Grapes of Wrath, when old, overloaded cars and trucks were always overheating in mountain driving?
— A.S.M.
Dear AS: This must be air conditioning day. No, the signs aren’t from the 1930s Dust Bowl days, because there were no air conditioners in motor vehicles back then. You can’t blame the California highway department and the CHP for not wanting Interstate 5 to be littered with overheated old vehicles. However, the signs seem to represent an excess of caution, because in newish cars, whose cooling systems are in excellent shape, climbs over the Grapevine, even on very hot days, do not strain cooling capacity enough to require turning off the A/C.
The power and condition of your engine — more power means less strain to operate the A/C — and the loads you’re transporting do matter, of course. So if you’re driving a 1991 Ford Escort wagon carrying six large adults with their luggage piled high on the roof rack and pulling a trailer, even turning off the air might not be relief enough.
On the other hand, if you’re driving a late model Ram V-10 carrying two small adults and a Chihuahua, you’ll keep your air on and not to worry. It’s wise to slow down, though, while climbing long, steep hills in super hot weather such as we’ve been having lately, to avoid stressing your cooling system.
Get familiar with your engine temperature gauge. Know where the normal range is for the needle position, so you’ll recognize when it moves significantly to the right to indicate true overheating, which can do serious engine damage. Whether you have the Matrix with the 126 or the 164-horsepower 1.8-liter engine, you should be able to make it over the hill nicely with the A/C left on.
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