My car has have climate control, and I'm certain it routinely mixes hot and cold air. I almost never touch the controls, so it's a bit hard to tell.Prior to climate control, I ran the A/C 365 days a year, as well as the heater when needed. Heating is free, and the A/C adds an imperceptible amount to the fuel consumption. The result is dry air, no fog, no need to open windows or wipe windows, cooler air at face level and warmer air at foot level. All good safety and comfort features, which many people have not been able to understand.