No short­cut ‘switch’ for a faster warm-up

The Maui News - - AUTO - By Ray Magliozzi

Dear Car Talk:

I have a car-re­lated ques­tion that’s been both­er­ing me for a while. I was born and raised in a place where heat was far more of an is­sue than cold, so I grew up learn­ing that at high tem­per­a­tures, us­ing the heater for the pas­sen­ger com­part­ment could be used to cool the en­gine if it started heat­ing up too much. Now that I’ve moved to a place where it snows, I’m be­ing told that when it’s cold, us­ing the heater ac­tu­ally will warm the car faster, be­cause the ther­mo­stat will re­quest more heat from the en­gine, caus­ing it to come up to tem­per­a­ture faster. True? Thanks! — Pa­trick

False. You’re wel­come.

The first part is true. The heater is, es­sen­tially, a smaller ra­di­a­tor that lives be­hind your dash­board. And when you turn it on, you draw heat away from the en­gine and into the pas­sen­ger com­part­ment.

If the en­gine is start­ing to over­heat, ad­ding even a small ex­tra ra­di­a­tor will help cool the en­gine — even if it ends up melt­ing your Crocs.

But con­trary to your wish­ful think­ing, Pa­trick, draw­ing heat away from the en­gine will not make the en­gine warm up any faster. There’s no “switch” or “ther­mo­stat af­ter-burner” set­ting that com­mands the en­gine to warm up faster if you ask for heat. It’s al­ways warm­ing up as quickly as it can.

So if your pri­mary goal in life is to get heat as quickly as pos­si­ble, your best bet would be to start the en­gine and, with the heat off, drive away im­me­di­ately (driv­ing warms up the en­gine faster than idling). And then check af­ter a cou­ple of min­utes. When the air com­ing out of the vents is no longer colder than the air in the car, leave the heat on. Or, if you’re lucky enough to have a tem­per­a­ture gauge on your dash­board, then just turn on the heat as soon as the tem­per­a­ture nee­dle moves at all.

By the way, most cars that have cli­mate con­trol do this for you au­to­mat­i­cally. They’ll let the en­gine start to warm up and wait un­til there is heat be­fore they start blow­ing any kind of air on you.

Now, once you turn on the heat, you’ll cause the en­gine to take a lit­tle longer to get to its full op­er­at­ing tem­per­a­ture. But when your frozen butt cheeks are tee­ter­ing on the folds of your rock­hard leather seats, who cares about the en­gine?

It’s true, the en­gine won’t run at its most ef­fi­cient un­til it reaches full op­er­at­ing tem­per­a­ture, but you won’t harm your en­gine by de­lay­ing its warm-up a lit­tle bit — es­pe­cially if you’re driv­ing it gen­tly.

Af­ter all, you’re an Amer­i­can, Pa­trick. And as such, you are en­ti­tled to life, lib­erty, the pur­suit of hap­pi­ness, and au­to­mo­tive heat at its first avail­able mo­ment. Claim those rights.

Got a ques­tion about cars? Write to Ray at Car Talk in care of King Fea­tures, 628 Vir­ginia Drive, Or­lando, FL 32803, or email by vis­it­ing the Car Talk web­site at

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