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Aircon fault code 18.3 - how to fix it?

koonl Oct 15, 2006

  1. koonl

    koonl Member

    Hi all,

    Running the OBD from the climate control on my 98 A3 1.8T, I'm getting 18.1, then 18.3 which is "Fresh air voltage sporadic".

    I ran the diagnostic after noticing a squeaking noise from under the bonnet when the cooler was on, either with the aircon on or not. I thought it was just a fan as the squeaking would slow down or stop the lower I adjusted the speed. The next time I switched the car on a few hours later, I noticed the fan wasn't coming on at all despite the speed of the fan or temperature selected. The snowflake would come on if I pressed the aircon button, you could feel the compressor come on but absolutely no air out of the grills. This is the same when pressing the demister button. After about 5 minutes everything started to run again as normal.

    Outside temperature was around 20 degs, so it's not that it was cold. Besides, you wouldn't be able to start the aircon and see the snowflake if it was too cold.

    Anyway, 18.3 was the code I was getting when it wasn't working, and ran it again when it was and then the error cleared. Does anyone know exactly what the problem is, or what it could be, and how to possibly fix it? Is it a DIY or a garage job? Thanks

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