I have a 2006 A3 2.0Turbo, the air conditioning is currently blowing hot. Here are the diagnostics so far:

Tested pressure low was about 80-90PSI, high was 90-100PSI. When reved to 2000RPM, the pressures did not change.

Cannot locate the high pressure switch, but have been told by the local Audi dealership, the high pressure switch can be a problem.

Does anyone have any suggestions on locating this switch? Determining what the root of the problem is?

Would greatly appreciate any feedback!!

 

If you never replaced the AC in your Audi - get ready for the worst case scenario. I too had it die on me... first it was that High/low pressure switch (located in the front passenger side of the engine bay. Stand in front, look behind the radiator and you should see it towards the bottom).
Once the switch was replaced it worked great for another couple of months until the compressor died. I had to replace everything (compressor, drier, etc). Total bill is around 450 in parts + labor (unless you DIY like I did).

Unfortunately Audi installed a very crappy AC unit in the A3 8p models. I have not seen a user that made it over 80k before the unit died and had to be completely replaced.

Great place for replacement parts is RockAuto Parts Catalog

 

Thank you Sheldon!