When I bought my car a couple of years back, it had already been converted to R134-A. I live in Dallas and I have no complaints about the AC's effect.

The one thing that I have noticed is that if I am at a stop sign, the climate control kicks up the AC fan speed. But a minute after I start moving and as the engine rpm picks up, the AC fan speed decreases. I'm sure that happens with an R-12 system too.

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1986 300E (3/2002) Rear ended and totaled (10/2009)
2000 Xterra (5/2000)
1992 400E (11/2009) -Sold
1986 300E (12/2009) - Sold
2004 E500 Wagon (6/2013) - Sold