Noticed there are a few Aircon threads now that the hotter weather is here. Assuming the recirc motor is working, and AC light comes on when aircon activated, here's a cheap test for aircon efficiency.

You need one of those cheap internal/external digital temperature gauges, available from most car accessory shops. These come with an external temperature probe on a flying lead.

Switch aircon on and set vent control to face vents only. Set fan speed to 3 and temperature dial to coldest setting. Push the probe into one of the face airvents, and allow about five minutes to get the minimum temperature reading.

If aircon is workng to max efficiency, the reading should be 4c or lower

If aircon has lost about 20% gas, expect about 10c

If aircon has lost 50% gas or more, temperature will be close to outside ambient air.

Digital temp gauages are roughly a tenner.

Aircon fault codes are not displayed with the cheaper fault code readers, so you will need VAGCOM or one of the more expensive code readers to fully test your aircon.

Simples.

LOVIN your sig!