Why your car loses power when you turn on the AC

Last night I walked out of my office and was blasted with  hot air, like someone was aiming 40 hair dryers at me, and today is going to be even worse. Seeking refuge,  I got into my car, and promptly turned on the A/C and set the climate control to 60. As the dash thermometer crept past 102 degrees, I was perfectly comfortable. Technology FTW.

Some might notice it, but when you turn on the air conditioner, your car can lose up to 20 HP. If you are cruising and engage the air conditioning, its more evident than going from a stop, but there is usually a performance loss no matter what type of vehicle you drive.

But why? There is nothing wrong with your car, this is the way your serpentine belt is routed on your motor. You see, the belt is turned by the engine, and drives thing like your power steering pump, alternator and water pump. Typically the belt routing also drives the A/C compressor.

When you hit the button to turn on the air conditioning, a clutch is engaged that adds resistance to the belt, because the belt is now working harder to turn more items then before. This is also why some people might notice a drop in gas mileage.  if you need a little bit more power when merging or when you know you will have to accelerate, you can always stop the system and then restart it.

[caption id="" align="aligncenter" width="400"] This is a typical layout of a serpentine belt that drives your engines functions[/caption]

People have also asked me why their car leaks water when the AC is on -  this is also something that shoud nto be a concern. The AC condenser drips water as it cools the air it sucks in, and this is normal. n fact, you should only be concerned if your car is not dripping water when the air conditioner is on, as this typically indicates a blockage in the line or malfunctioning condenser unit.