The ability of cars to handle higher volatility fuels has been increased steadily through the years, but use of power accessories makes further improvements more difficult. Air conditioners are of particular concern because large amounts of heat are added to the engine using condensers which interfere, per se, with the cooling system.
The effects of air conditioners on fuel volatility requirements are of immediate concern in Texas because the market has been concentrated: about one third of units sold to date are in Texas. Sales are spiralling, however, and they will be of general interest soon: total sales to date, 260,000; 57,000 in 1954; 176,000 in 1955; predicted sales of 1.0 million per year by 1959.
Tests on twelve air conditioned cars showed that car RVP limits were reduced 0.7 on the average when the units were operated. Tests on three cars before installing one type of unit showed that car RVP limits were reduced 1.3 on the average when the units were installed but not operated and were reduced an additional 0.6 when the units were operated.
These data illustrate the major magnitude of the automotive air conditioner problem. It is hoped that the excellent progress made to date in improving the ability of cars to handle higher volatility fuels can be continued while including optional equipment such as air conditioners.