Half-hearted A/C on 99ºF ride

[Cousinphil]

My wife and I took the Audi on a road trip last weekend to her niece's wedding in Litchfield, CT. It had been a while since we had driven out of Maine and as we drove south into New Hampshire the traffic was getting heavier and the mercury was climbing into the nineties. When we crossed into Massachusetts the highways were clogged with cars. We started getting delays. The traffic, which was generally traveling at about 75 mph, would all of a sudden become a sea of brake lights and everything ground to a halt. The traffic would inch forward for a half hour and then resume speed seemingly without cause. No construction, no accidents, just too many cars. It happened again and again. The temperature went up to 99º and we couldn't help noticing that the air coming out of the dash vents was warm if not actually hot. "This is not cool," said my wife. She has been known to get cranky when she gets overheated.

So we made it down to Litchfield and were able to shower off the sweat before the rehearsal dinner. Driving back north, the A/C worked at first but then stopped working again. At one point the vents shot out a big spit of water which hit us at about neck height. And then the A/C worked flawlessly for the rest of the trip. I have no idea what the problem was.

I don't use the A/C much in Maine. Usually I have all the windows and the sunroof wide open and enjoy the breeze.

[diagnosticator]

Unless you are worried about the extra fuel used, run the HVAC in AUTO mode regardless of outside temps, more often. Even if you have a window open. The dehumidified air will feel cooler. Also, the drain for the evaporator core is plugged up, allowing an accumulation of condensate in the evaporator. If there is a lot of condensate in the evaporator, will definitely reduce A/C performance.

[Cousinphil]

Ah. A plugged up evaporator core drain. This sounds like an easy fix. Sounds like a coat hanger might be the tool. Where the heck is the evaporator core? Under the hood? In the cabin?

[Kevin C]

Ah. A plugged up evaporator core drain. This sounds like an easy fix. Sounds like a coat hanger might be the tool. Where the heck is the evaporator core? Under the hood? In the cabin?

http://www.audizine.com/forum/showth...2742-A-C-drain

The thread bounces around a bit... but has some good info.

Also, check your passenger side carpets for water, typically some water will be present if you have a clogged drain (It might be hiding in the low spots underneath).

[Cousinphil]

I usually run with the Econ button lit because I get better performance out of the engine. The difference is subtle but definitely noticeable. With the A/C on I don't have as much power going up a hill in the higher gears. Especially at low RPMs.

But I seem to remember that it's a good idea to run the A/C from time to time. I don't remember why.

[Gin+]

I'd still consider checking for the proper amount of refrigerant.