Not always cold air

In the past, I'd always used cold air to get rid of smog by blowing to windshild. Recently I rented a Mercury Milan, a very nice car with 27 mpg over a 1000 miles highway stretch; whenever I pressed the windshield blower, it automatically blowed out hot air and instantly the smog was gone.

In your case, maybe somebody turned the temperature scale to hot (when mechanic test-drove your car, he might turn it to hot due to the cold weather). Anyway, it isn't a false function.