The time-old ON/OFF air conditioning debacle

Dear Car Talk

Dear Car Talk | Sep 01, 1990

Dear Tom and Ray:


I wonder if you can answer a question in order to solve an argument I'm having with my husband. Is it better for the car engine if you turn OFF the air conditioner before you start the car, and then turn it ON after the car is started? Thank you.
Mrs. Smith

TOM: Well, Mrs. Smith, our philosophy has always been to turn the air conditioner on in April, and turn it off in October. But the answer to your question is that it doesn't matter. When the starter is engaged (when you turn the key to the start position), all of the major accessories are momentarily turned off anyway. The instant the engine starts, they automatically come back on.

RAY: So you're both right. The air conditioner should be turned off when the car is started, but it's done automatically, so you don't have to do it.

TOM: So technically, it doesn't matter. But we don't limit our answers to the technical realm. We suspect that this argument has roots that go deeper than the car's air conditioning system. So as unlicensed and uninvited marital counselors, we'd like to suggest the following: When Mr. Smith is in the car, do it his way. And when he's not, do whatever you want.

Get the Car Talk Newsletter