i have an A4 2L 02 model on cold frosty mornings the air con struggles to keep the front window clear the more people in the car the worse the proplem is. theres no hope of keeping the rear windows clear at all. theres a new pollen filter in the car the dealer has no idea wat the problem is . any body got any idea ?

 

well could just be that too much moist air in car for it to work well, but i dunno, i am a EPA 609 certified AC technician, and its really hard to explain what it is you should check, refrigerant is a great dehumidifier and sucks moisture out of the air in its own nature. a low charge condition can cause a rapid cycling air conditioner that will never really stay on long enough to work well, as well an overcharged ac system will cause the system to be totally INEFFECTIVE. basically the best way to think about the AC system in lamens terms is that the system needs to operate on as low of a charge that will allow the system to operate properly, now i dont want someone responding and arguing that fact cuz i know how its said there can be taken wrong way, i just dont wanna write a 4-page post on the thermodynamics of an AC system. anyhow what you need to get if you want to check out your ac system is a set of air conditioning manifold gauges, i know for a fact the only port on my a4 availbe is a high side port but maybe they put a low side port on the 02 and up models, anyhow what you do is hook up the gauges to the manifold gauges and open the service taps on the LINES them selves, do not open the taps on the manifold the gauges attach to, they should remain closed or else you will emit refrigerant into the eviroment through the yellow charge hose, anyhow with the gauges hooked up turn on your AC system, and look at the high side pressure first, you will see that the pressure goes from a lower pressure to a higher pressure, at the point the high side gauge is at its highest pressure the pressure you should have on the gauge is according to this formula given here : Ambient Tempature (outside air)x2.42 , so for example say its 90 degrees outside it would be 90*2.42=218psi high side pressure. now you will see this number kinda osciallate around because there is a thermo valve that prevents evaporator freeze up so the number should go up to that 218 for example and stay there for a bit then back down and then up again. ohh yea you need to be at 2000rpms when you do this as well. if you are attached to the low side you should see the low side osciallating from like 40psi down to like 20psi back and forth that would indicate a good working ac system but the highside indicates your charge, if your psi is too high you need to let some refrigerant out, if its too low you need to add some and can do it with the cans of r134a they sell at the auto parts store using the same manifold gauges. the manifold gauges and refrigerant are avaible at pretty much any auto part store, just make sure you dont buy cheap gauges, a good set of gauges is about $100.00 and is very important to make sure you get accurate readings. i hope this has helped in some kind of way cuz took way too long to type.

 

ever seen this button its for internal air ensure its switched off
if its on thats why your windows steam up

[IMG]local://upfiles/12092/378BABAC81404431A043D47173E44744.jpg[/IMG]

 

Wow brewmstr that was one hell of a post with all the right info

Im also 609 certified but I still cant remember all that nonsense

And I absolutly hate all the info that comes along with A/C


The only problems I ever see with Audis is if you have a low charge so check that first
You do have airflow out of all the vent positions right?

And if you have a VAG there are a bunch of MVB(measuring value blocks) to see whats going on
If i remember correctly its in MVB 12 not really sure
In field 1 there are one digit numbers that correspond to the compressor shut off stages

 

oh yea i forgot something lol, buts its easy, when checking out the high side pressure it should the low end of the range is the amb temp*2.42 and then the high end is amb temp*2.42+40 so basically with that 90 degree example i gave you the high side pressure would be anywhere from 218-258psi. but you want it on the low side of the range. to the point where the air conditioner dosent cycle too rapidly, that might be hard for you to recognize because the system will cycle frequently but a fast rapid cycle is not good.