Heating and Air Conditioning: Description and Operation

Electronic Touch Climate Control Panel:

This system automatically regulates and maintains operator selected in-vehicle temperatures from maximum "COOL" to maximum "HEAT" regardless of changes in outside air temperature. Particularly during humid weather to increase passenger comfort, and limit window fogging and condensation, this system removes excess moisture from the air when the A/C compressor is engaged and operating.
This system is similar to other electronic touch climate control systems, Fig. 2, but incorporates new features such as a digital microprocessor (MPU) with a programmable memory, a hidden diagnostic switch for system self-diagnosis, individual in-vehicle and outside air temperature (OSA) temperature sensor signal inputs to the MPU for improved temperature compensation, a digital vacuum-fluorescent display, an English-metric conversion capability and an optional rear window defog key pad switch.

While all electronic touch climate control systems use an electrically operated, rheostat controlled motor to position the A/C-Bi Level-Htr (temperature) valve, this system uses three programmer controlled vacuum actuators for positioning the OSA/RECIRC, A/C-DEF and A/C-HTR air flow valves.

These systems control components include an A/C control head assembly (controller), programmer assembly, blower power control module, in-vehicle temperature sensor and aspirator, outside air temperature sensor, A/C module containing the air flow control valves, the evaporator and a heater core. Combined with the cycling clutch orifice tube refrigeration system, the controller regulates blower fan motor speed and generates command signals addressed to the programmer and blower power control module.