While installing a new temperature sensor in the left heat control flapper, I noticed a small line (the inside diameter about an 1/8" or less), I assume is a vent line. It is broken just where it goes into the engine compartment. It is next to the A/C line. Any idea what it is or what it is suppose to do? Thanks for all advise or ideas. 1979 930

 

A picture is worth a thousand words...

 

I agree a picture would be good, but I was not able to get a clear shot. All I can think of is a vent line back from the fuel tank. If I pull the air cleaner I might be able to follow it to the end.