What Your Car's Air Conditioner Actually Does

During the gruesome heat waves, do you long to hop in your car, turn on your air conditioner and feel that cool, crisp air? Much to your dismay, you turn it on and find it to be mildly cool and somewheat humid still. Uh-oh... is your car's air conditioner on the fritz?

As my climate-control professors would remind me, the purpose of air conditioning is to provide cool, dry, and clean air.

Cool. Your car’s air conditioning system uses pressurized refrigerant to transfer heat from the passenger compartment to the outside (ambient) air around your car.

Dry. The air conditioning system works to remove humidity (moisture) through the evaporator.

Clean. While the evaporator may also act as a filter for the air conditioning system, the cabin air filter is the first line of defense in preventing contaminants from building up on the evaporator. Another function of the cabin air filter is to filter most road dust, allergens, and exhaust fumes. More on this little but often overlooked filter in future posts (stay tuned!).

All of these functions are relative to the ambient temperature. The system is limited in the amount of heat it can transfer and the amount of humidity (moisture) it can remove. So on very hot and humid days (especially during heat waves), you’ll find that the air conditioning in your car is not as effective compared to warmer and drier days. Remember, the A/C system provides cooler, drier, and cleaner air into the car compared to what is outside the car.

Before jumping to the conclusion that there's something wrong with your A/C system, try it again the next day when the weather's not as hot and humid. If you find that you've got that cool, crisp air back then your air conditioner is functioning as it should.

Image via freedigitalphotos.net