Where is the AUDI TT air-con low side port?

The low side service port for the air conditioning system in an Audi TT is typically located on the larger diameter aluminum line that runs from the evaporator to the compressor. It is usually found near the passenger side of the engine bay, close to the firewall. To access it, you may need to remove some engine covers or components depending on the model year. Always consult your vehicle's manual for specific details.