Auto. A/C Systems: Components: Programmer

The programmer consists of a compensator assembly, a vacuum motor, a vacuum checking relay, vacuum water valve, output linkage and control linkage. The programmer is mounted on the heater case and is connected to the temperature door by means of a threaded rod from the heater case. There are four input connections to the programmer:

1. A vacuum connection from the vacuum harness supplies engine vacuum to the vacuum relay.
2. A temperature control (bowden) cable from the control panel attaches to the control linkage of the programmer to position the programmer for the desired comfort level.
3. An ambient air housing from the air inlet supply to the ATC system is connected to the compensator assembly, which provides a sample of ambient (outside) air so the programmer can regulate outlet air temperature to compensate for outside air temperature changes.
4. An in-car air source hose is also connected to the compensator assembly. The movement of ambient air from the air inlet at the blower motor through the ambient air hose causes air to be drawn through the instrument panel grille and in-car hose to the compensator. This provides a sample of in-car air to the programmer to allow regulation of air outlet temperature to compensate for temperature changes inside the car.