Weather Eye

The Weather Eye was a trade name for a Nash Motors-designed fresh-air system for automobile passenger compartment heating, cooling, and ventilating. The Nash "All-Weather Eye" was the first automobile air conditioning system for the mass market. The use of the Weather Eye name for automobile passenger heating and air conditioning systems continued in American Motors (AMC) vehicles.

The design principles of the Nash Weather Eye system are now in use by nearly every motor vehicle.

In 1938, Nash Motors developed the first automobile heater warmed by hot engine cooling water, and using fresh air. This "Conditioned Air System" is characterized by a cowl-mounted outside air receiver that passes fresh air through a heater core utilizing hot engine coolant for a heat source. The Nash system also pioneered the use of slight pressurization within the passenger compartment to eliminate the infiltration of cold outside air during winter use. This was a fan-boosted filtered ventilation and heating for the passengers, not the modern meaning of an "air conditioning" system. Nash was also the first automobile to make use of a disposable filter in the air-intake to clean incoming air.

The Nash system was a major advancement compared to what was used up to that time: heating by recirculating the air inside the car.

A concurrent development, the Evanair-Conditioner was offered by Hupmobile on their 1938 and 1939 model cars.

In 1939, Nash added a thermostat to its system, making it the first thermostatic automobile climate control system. The Weather Eye "was the first truly good heating and ventilating system." Additionally, defoggers (defrosters) were incorporated with the introduction of the 3900 series cars that year. The Nash HVAC system was designed by Nils Eric Wahlberg and it continues to be the basis for use in modern automobiles. Nash included the first automatic temperature control for the airside of the heating system with the thermostat sensing the temperatures of the incoming outside air, the heater's discharge, and interior of the car; so that a change in any of these three air temperatures resulted an automatic adjustment to maintain passenger comfort. Nash's Conditioned Air System heater was now marketed as the "Weather Eye" and consumer sales literature explained that the thermostat's "mechanical eye" watched the weather, hence the name.

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