Programmer Description

The heater and A/C programmer (1) contains a microprocessor that controls the electronic A/C system. The programmer receives electrical signals from the following components:
^ The heater and A/C control
^ The passenger climate control
^ The right and the left sun load sensors
^ The ambient air temperature sensor
^ The inside air temperature sensor
^ The [1][2]blower control module
^ The powertrain control module
^ The driver and passenger air mix valve actuators

A microprocessor in the programmer processes the signals. The microprocessor then sends commands to the system components that control the following elements:
^ The A/C compressor clutch operation
^ The air intake location
^ The air discharge location
^ The air discharge temperature
^ The blower speed

Four solenoid-actuated vacuum valves control the air intake and discharge locations These valves are located inside the heater and A/C programmer. Each valve controls the vacuum to a different vacuum actuator. By energizing various combinations of these solenoid-actuated vacuum valves, the heater and A/C programmer may control the direction of the air flow to the following locations:
^ Floor outlets
^ Panel outlets
^ Defroster outlets

The programmer also controls the source of the air flow:
^ Fresh (outside) air drawn into the system
^ Inside air is recirculated

The heater and A/C programmer also performs self-diagnosis functions for the electronic or for the dual zone system. The microprocessor identifies faults when the system is operating. The microprocessor stores this information in memory. When the system diagnostic mode is activated through a scan tool, these faults are displayed as a numeric Diagnostic Trouble Code (DTC).