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How does Max. A/c affect engine performance?

Does enabling recirculated air cause the compressor to work harder in any way ?

No. The compressor doesn’t care. The compressor is designed to develope a certain amount of pressure of the refrigerant in the A/C system. What you do with the cooling effect of the A/C is up to you.


Max AC makes the compressor work ever so slightly less hard. Why? Max AC switches the air inlet source from outside (fresh) to inside (recycle). When fresh air is coming in, there is almost always more moisture coming in. It is much harder for the AC to squeeze water out of the air than it is for it to just cool air. On the recycle setting, it only has to remove the moisture you add to the air.

Allow fresh air into the car to mimimize headaches and dizziness and carbon monoxide poisoning and things like that. Max AC helps to cool down a hot car when you first get in. It’s a legitimate question but should have little effect on anyhing if you use recirculated air minimally. In reply to the next post, “not enough air.”

This is 100% true.

It might be also important to know that, when the recirculation setting is used, it doesn’t recirculate 100% of the passenger cabin air. This vent system setting also allows some outside air to be introduced.


actually the normal AC will cool down a hot car faster since the interior of of a car parked in the sun is almost always hotter than it is outside. When you use Max AC you are reciculating the interior air. In this case the outside air is cooler, which means it will be easier to cool than the interior air.

This is not true for most areas. Example: If it is 80 outside, but 120 inside the car. It will still cool the 120 degree air quicker because once the initial humidity is removed, the air stays pretty dry. If you set it to fresh air, it constantly has to remove moisture from the air. If you remember high school chemistry, it takes much more energy to convert water from a vapor to a liquid, than it does to cool low mass air. You may not believe this, but it is very true, and if you cared to measure results, you would know which way really cools quicker.

From personal experience I’ve had better success using normal AC for the first two or three minutes then switching to Max AC for the rest of the journey. With both of my cars that have AC this procedure offers the coolest air in the least amount of time. When just use Max AC right off the bat, it takes a little longer to cool down. I live in Virginia, so it’s usually pretty humid here in the summer.

Show me the data and I will believe.