An air conditioning apparatus including a heater or furnace includes a controller for receiving control signals from a thermostat and from a user interface for initiating a contingency mode of operation when a signal from the thermostat is not available. The user interface includes a visual display and multiple keys for entering the contingency mode which includes selecting a capacity of heat output of the apparatus and a duty cycle. The user interface may be disposed in the apparatus cabinet and connected directly to a microprocessor based controller for the apparatus. The contingency mode is automatically aborted if a fault signal is received by the controller, a signal is received from a thermostat or power to the apparatus is interrupted.