Ah yes, the old "AC leaking water" trick
 

93 notch AOD. 50K miles. My ac blows nice and cold, but i see water leaking under my car when my ac is on. The higher I push the compressor, the more water that leaks. I've also seen this on some other cars (including a brand new Scion coupe).

What is the cause of this?

Re: Ah yes, the old "AC leaking water" trick
 

It is called condensation. I don't know the exact science of it...but the a/c lines get cold, warmer air hits the lines which causes the condensation...which in turn produces water. Same concept if you take an ice cold beer mug out of the fridge & set it on the table. Pour beer out of the fridge (which is warmer) into it and water will begin to drip down the sides of the mug. It's completely normal.

Re: Ah yes, the old "AC leaking water" trick
 

Yes it is normal. As long as it drips outside the car and not inside on the floorboard.
The evaporator coil (inside the dash) has freon running thru it and accumulates the condensation into a housing which drains thru the firewall. If the drain line clogs the water will back up into the floor and you will have wet carpet and smell.

Re: Ah yes, the old "AC leaking water" trick
 

Yes, but what if my car has a LOT of condensation/leakage?


For example, when I get out of my car and close my door (after driving with the AC on), I hear a "sheeesh" (sounds like air being released) when the door is slammed. For the longest, I wondered what that was until I discovered that its water hitting the ground. So, it seems that I have more condensation/leakage than normal. Is THAT normal?

Re: Ah yes, the old "AC leaking water" trick
 

its normal. the hotter it is outside the more humidity it pulls out of the air.
the noise u hear is the sizzling of water hitting the hot exhaust system.

Re: Ah yes, the old "AC leaking water" trick
 

If you just discovered the concept of water dripping underneath a car that has had the a/c running...then how do you know what a "normal" amount of water would be? That "sheeesh"...or "sizzle" sound you hear is totally normal. How big (diameter) of a puddle do you have under the car?