Whunter and Leathermang, mention that the rules are different for R12 vs. R134, and that the sight glass is not a good indicator when the ambient temperature is below 70F. What are the differences that one will notice in the sight glass between these two gases?

Its now 35F outside here in Montreal, and I noticed bubbles in my car as well ('95 E300 Diesel with R134) I am therefore wondering what the bubbles in the sight glass indicate.

Will these bubbles disappear once the ambient temperature reaches 70F?

__________________
'95 E300 Diesel, 264,000 Miles. [Sold it]