ermm.... hard to explain.
It Just doesn't work, won't get cold air in summer.
05 TDI to about 07 had a glitch in the ECU and it just doesn't work.
I honestly didn't believe it, but lot of knowledgeable told me that is the issue.
I bought a newer revision 2.0 TDI BKD (4motion) ECU (think the newest same base spec was from a Tiguan)
Anyhow.....got a specialist to clone the data from my old ECU, into the new one, swap them over and it the Aircon worked. Just like that!
Before the ECU change I just swapped back to the old control panel, in the few hot summer weeks we have.
soon as it cooled down, the new panel was fine. blew cool air but not COLD
Last year, after the ECU swap, had COLD air all summer .... superb