[s-cars] AC compressor shuts off at 42 degrees F

[David Forgie]

While you might not like it or agree with it, what you describe is 110% normal operating procedure. In Canada, running in metric, the cut-off is +5C (I know 4 C = 39 F so 5 C is about 41F). 

Audi's "logic" was that below that there is a risk of freezing up the condenser. Which has to be complete BS. I had a 1986 Jetta Carat with Air Con and it would come on with the defrost position on the manual 
HVAC controls and it would do this well into the minus temps. Never an issue. Worked fine. 

So you have to live with it or figure out how to reprogram or trick the auto climate control system. 

/Dave F