Abstract: An integrated precision humidity and temperature control system of research laboratory quality is disclosed in which air flow, water spray and refrigeration apparatuses are sequenced automatically by solid state controls linked in a cooperative manner. Very stable and precise relative humidity and control air temperature constancies are maintainable.

Abstract: An environmental chamber for testing objects, such as electronic components under climatic conditions, in the range of 80.degree. C. to 150.degree. C. and relative humidities in the range of 70% to 95%. The test chamber is pressurized and supplied with moisturized, heated air to obtain the desired climatic condition, the climatic condition being maintained by surrounding the test chamber with an insulated housing. A double door arrangement is provided to effect a pressure seal and for isolation of the test chamber from any appreciable heat loss.