Cadillac Repair: air conditioning conversion to r-134a, 134a freon, r 134a

Question
Is this an expensive procedure or is it relatively simple and cheap? My caddy is a 1986 Coupe DeVille with 63,000 miles on it.Last night it started acting as if possessed and kept running the air conditioning fan after the engine was shut off.It would not allow me to select the auto mode and kept switching over to econ mode.

Answer
You CANNOT use R-134a freon in this R-12 system as the low pressure sensor is NOT calibrated to be used with R-134a freon.

If you install the R-134a freon you will experience CHECK ENGINE light illumination on the dash and constant AC compressor disengagement. To date their is NO fix for it.