Blue Pullman

Air Conditioning

The air conditioning system was designed to provide and maintain an automatically controlled clean conformable atmosphere within established limits of temperature and humidity irrespective of outside ambient conditions. This required provision for heating, cooling, air filtration, car insulation and a degree of manual temperature selection for service requirements. In addition to the attraction of a high standard of passenger comfort, the air conditioning also kept clean and fresh the upholstery, fittings and other appointments.

Each car was appointed with a roof mounted air-conditioning unit, floor heaters, automatic control panel, and a refrigerating unit. The conditioning unit filtered the air, removed excess moisture, and either cooled or heated the air as required.

A proportion of the air in the car was extracted by roof ventilators and this was made up by admitting filtered fresh air into the system. Heating was by electric heaters and cooling was by flowing the air over evaporator coils of the refrigerator. Excess moisture was deposited as dew on the cold coils of the evaporator.

The motor-driven compressor and condenser were mounted on the underframe and used Freon 12 or Arcton 12 as a refrigerant. The condenser was cooled by two-motor driven fans. The manual temperature-control switch enabled the heaters to be switched on at car temperatures of 68, 71 or 74 degrees F., automatic control being by Vapor thermostats. To ease the load on the power supply if the air-conditioning compressors throughout the train were switched on simultaneously, a delay switch was fitted to give a sequence switching throughout the train.