I just bought a 96 A4 quatro with the V6.

I bought it knowing the air conditioning doesn't work. I bought it from the original owner with EXTENSIVE and perfect maintenance history. The car has had all its oil changes and maintenance done at the dealer to include timing belt and water pump. Needless to say, it drives like a dream. Then again, its my first Audi.

Anyway, I've noticed that the windows will slowly fog up while driving. Keep in mind, the air conditioning doesn't work which would help with the humidity right? (previous owner said he thinks the compressor is bad but that it might its need a re charge).

Now, there are no signs of a bad heater core that I can tell. No bad smell, no water on floor and the heater works great! I've noticed that if i just crack the sunroof; problem solved. Seems like its its humid in the car. It was raining out, i parked the car, went in to the mall for a couple hours and came out to my windows foggy. Any ideas? Clogged drain of some sort? You think getting my air conditioning fixed would help?

Thanks for your time. I friggen love this Damn car!

 

i think the defroster runs off of the A/C, so if defrost won't fix the fogging, i'd start there.

 

I sure hope so. Just can't figure out why it would fog up after walking away. Thanks.

 

Do you have the air blowing at all? I don't have AC in my car and if I am driving in the rain (humidity), my windows will fog up unless I have the air blowing, albeit warm air.

A likely place for water to seep in is through the hood release cable which is under the hood on the driverside right behind the ECU box. If the rubber grommet isn't seated properly, you could have a small water leak, though you would probably know it by now.

The AC compressor isn't too bad to replace, assuming the trinary switch, the condensor, the hose from the compressor to the condensor, and the evaporator are all in working order. The evaporator is rather difficult to get to

 

Thanks. Yeah, I do have warm air blowing. If I keep it on the defrost mode (again, no a/c) it seems to help. But after about five minutes, the widows start to slowly fog up. However if I just keep the sunroof cracked, they never fog up. I'll check that gromet. I also wonder if the evaporator drain for the air conditioning is clogged or isn't their a plug under the battery too?

 

I would suggest changing the temperature as that happens to see if it makes a difference. Thanks to recent nice weather, I've forgotten how much not having AC sucks. I think the fogging up would be more of the temperature difference between the outside and inside as opposed to humidity inside the car, though both come into play.

I can't help you on the evap drain, but if there's water under your battery, you'd be able to see it. Without a battery tray cover, leaves clog the drain holes and it'll fill up. It shouldn't be connected to the interior of the car, but then again.. it's an Audi

If you're set on checking drains, you could also check the sunroof drains. Open the sunroof (or if it's not fully functional, remove the glass only) and use an air compressor to blow air down through the front drain tubes, you'll see them without the glass in the way. You can also use a coat hanger to clear them.

More than likely, it's something else, but those are the drains I know of which are problem areas.

 

Sweet thanks, Ill check those out. Either way, for $2800 im pretty damn impressed with this car! A/C or no A/C

 

I live in the Charlotte area and as cooler weather came, I was having trouble getting the windshield to defog. I was unable to get much heat out of the automatic envirnmental control system (ECS) either. I thought that I had either a failed temperature control door (major bummer: the car was built around the dash, which would have to come out) or a clogged heater core. I pulled the plastic cover off the battery, the two heater hoses and back-flushed the core and - indeed - a bunch of white guck and a couple of spiders came flying out. Reserviced the radiator and bled (at the core, through the heater hose with the little pre-drilled hole) the system and thought: "probelm solved". Nope, still very little heat or defrost action.

Unrelatedly (I thought) I was vacuuming the car and took the little furniture brush around the dash, over the ***** and buttons. A big glob of dust came flying out of the little grilled area under the ECS controls at lower portion of the center dash. Apparently that is where the temperature sensor lives for the ECS system and its little temperature collection fan had been clogged by this dust mouse. Suddenly my air conditioning is no longer working full time, regardless of temperature selected and the defroster works just fine. An accidental fix.

 

My B5 fogs up in the rain unless I have the AC on. I think there is a tiny (for now) heater core leak which is causing it. When I up fire the car, and the heat is on, I can barely smell a little coolant. Strangely, this has only happened with the setting at 63-66F. Above that, no smell.

I've had severe heater core leaks in the past that cause persistent and dangerous fogging.

 

Yes, the A/C compressor cycles on when you have it set on defrost. It's the same in every car. You might not have a leak. Mine fogs up some when it rains too. I suspect it might be because the cabin air filter sits right under the passenger side windshield wiper cowl.