UK Car Repair: audi heaters, work colleague, audi a3

Question
my heaters on my audi a3 1.6 s reg are only blowing cold air any ideas whats wrong a work colleague told me to change my thermostat but dont know where this is located & im unsure this will fix my problem

Answer
Hi David, you do not mention which heating system you have on your Audi (computer controlled or mechanical dials) if the engine is getting hot then it is definitely NOT the thermostat. Here are my suggestions:-

1) Computer Controlled: It would seem to me that the actuator for the heat blend gate has either become faulty or disconnected or the computer which controls it has become faulty (Audi dealers can connect a code scanner to the A/C computer for around £70). The only fix for the actuator fault is to first gain access to the heater matrix by removing the central fascia panel. You will see the matrix, check the blend gate for movement. if you need to replace it you would have to contact your nearest Audi dealer.

2) Mechanical Dial: There is a cable running from the hot/cold dial to the side of the heater matrix and connecting to the heat blend gate. Check for connection of the cable at both ends and operation of the gate lever as there is a chance it is just stuck if you are lucky. Hope this helps - Paul