2007 Alhambra air con not working

I'm sorry my first post is a question, but here goes

2007 model 2.0 tdi BRT motor. Stylance model with climate control. I noticed the air con wouldn't go cold when we had a warm day a couple of weeks ago. I initially assumed I needed a regas and so took it in to a local garage for it to be done. 90 minutes later they told me the system was already full, however there was a problem. We both had a lack of time on a Saturday to investigate, although they initially found only 0.3v down at the compressor.

Since then we have been through as much of the system as possible (me and a tame mechanic, but not an air con guy) and can't seem to find anything wrong. I've swopped over the 454 control module relay thingy with no joy, we put 12v into the aircon clutch and that clicks in fine. The display shows all the correct temps and when put down to 'Lo' the fan churns away doing its best to chill things, but it only blows lukewarm. All the fuses are intact.

I'm in the process of changing cars and would like to sell it on working, in the nearly 12 years I've owned it I have always ensured it was kept in tip top condition, but this area is beyond my expertise. Before taking it into a specialist is there perhaps something else I can look at?

Scanned for codes?

Oh yes, forgot to mention that, the system is clear of codes. Everything's working fine, you can go up and down the temperature, side to side, auto and econ, and switch it all off etc. .etc. Everything that is apart from the compressor getting powered and cooling it all down. Or conversely heating it all up. All that gets blown through is ambient-ish air it doesn't appear to go HOT in demand, just warmish.

What was used to scan for codes?
Checked the fuses?
Do the radiator fan(s) come on when the a/c is switched on?
Do the exposed alloy a/c pipes (ones with valves on) near the bulk head get cold after a few minutes when the a/c is switched on?

We used a Snap On unit as we don't have access to a VagCom type
all the fuses have been taken out and checked, all OK
no, the fans do not turn on, and the pipes don't get cold either

im now not too concerned as today I put a deposit on a Tiguan R-Line and it has been partxd as seen.

I wish i knew what it was though........

Probably the a/c pump or pulley has failed

It's a low pressure sensor that's failed. However i have now sold the car, thanks for the replies.

Just to try clearing this thread up as I see the OP has part exed the car now. I also had a/c failure but with plenty of gas. Found the system pressure switch which supplies a 12V signal to the compressor when there is sufficient gas pressure. The switch is mounted behind the front bumper on offside (RHD). I removed the bumper for access - quite easy once you have done it once - 3 screws in each wheel arch, 3 or 4 rivet type fasteners underneath and 4 bolts on the bonnet slam panel. Get the gas depressurised first ( must try to save our environment) then disconnect the electrical plug ( spike or electrical screwdriver needed to release the lock) unscrew the pressure witch body and replace. Refit is a reverse of removal then get it gassed up. Hopefully, job’s a good ‘un.

Bob