R-414B: A retrofit blend for R-12 refrigeration and air conditioning systems as well as automotive air conditioning systems. The pressure and system capacity match R-12 in 40°F to 50°F evaporators, and the discharge pressure in hot condensers is only 5 to 10 psi higher than R-12 (a benefit in automotive AC and warmer refrigeration environments). The temperature glide runs about 13°F in the evaporator. The addition of isobutane to this blend significantly improves mineral oil compatibility, particularly for high viscosity oils used in auto AC.
General Provisions for Automotive Retrofit Blends: Automotive air conditioning retrofitting is governed by Section 609 of the Clean Air Act. The specific provisions of this section which apply to automotive AC retrofit blends are 1) you can't top off R-12 with a blend, the original charge must be recovered first, 2) new fittings must be installed on the car which are unique and specific to the blend being used, and 3) when using blends that contain R-22 the system must have nylon barrier hoses installed to prevent leakage.
In stationary refrigeration systems running in high ambient temperatures the use of an automotive blend can relieve problems associated with high discharge pressures, however capacity will suffer compared to R-12, especially as evaporator temperatures get lower.