Man, what a blend that one is. HCFCs and Hydrocarbons:

HCFC - R414B

A blend of R-22, R-124 and R-142b with hydrocarbon R-600a (isobutane) added to improve mineral oil miscibility. This blend can be used to retrofit R-12 automotive air conditioning systems as well as stationary refrigeration systems. The pressure and system capacity match R-12 in 45F to 50F evaporators, and the discharge pressure in hot condensers is only 5 to 10 psi higher than R-12 (a benefit in automotove AC and warmer refrigeration environments). The temperature glide runs about 13F in the evaporator. The addition of isobutane to this blend significantly improves mineral oil compatibility, particularly for high viscosity oils used in auto AC.

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1986 300E 5-Speed 240k mi.