Abstract: An automated functional test system for PC circuit boards. The test system includes a test chamber for removably receiving circuit boards to be tested, heating and cooling systems for controlling the temperature in the test chamber, a display, a variable circuit board power supply and diagnostics memory for storing PC circuit board diagnostic software. A control system is coupled to the heating and cooling systems, display, power supply and diagnostics memory. The control system causes the circuit board to execute the diagnostic software during low temperature, high temperature and cycling temperature diagnostic phases. The diagnostic phases are sequentially and repeatedly performed during a test cycle. The cooling system is actuated during the low temperature diagnostic phases to cool the test chamber to ambient temperature. The heating system is actuated during the high temperature diagnostic phases to heat the test chamber.