CONTROL SYSTEMS, ESPECIALLY FOR HEATING, VENTILATING AND/OR AIR CONDITIONING INSTALLATIONS FOR MOTOR VEHICLES

The control means includes a keypad and display unit which is connected to a processing means which includes a user or input memory, a regulation unit for receiving sensed values of parameters, and an output memory for controlling the means whereby the various working parts of the installation are themselves controlled. Regulation of the installation by the control system can be overridden by operation of a special touch pad which acts on an automatic processing circuit, which delivers a blocking command to the output memory, thus "freezing" the contents of the latter. The automatic processing circuit also operates in this way when the ignition key is turned to energise the installation initially. The frozen or blocked mode can be cancelled by operating any of the touch controls on the keypad.