System Controls

WARNING: This page is about a different car, the 2003 Dodge Grand Caravan, 2003 Dodge Caravan, 2003 Chrysler Voyager, and 2003 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.

The A/C-Heater Control Module:

is fully addressable with the DRBIII®.
communicates over the Programmable Communication Interface Multiplex System (PCI) Bus.
provides an A/C request to the Powertrain Control Module (PCM) over the PCI Bus when compressor operation is desired.
uses input from the evaporator temperature sensor to prevent evaporator freeze up while maintaining optimum cooling performance.
for exports with diesel engines, provides a Cabin Heater activation request to the Front Control Module (FCM) over the PCI Bus when conditions are favorable for Cabin Heater operation.
provides a blower relay on request to the Front Control Module (FCM) over the PCI Bus when blower operation is desired.
controls front blower operating speed. The five speed settings are Low, M1, M2, M3, and High.
controls EBL operation.
on three-zone systems, activates and deactivates the Rear A/C-Heater Control.
on three-zone systems, controls rear blower operating speed. The three speed settings are Low, Med, and High.
controls the front and the three-zone system rear electronic door actuators' operation.
- A simplified control system for operation of the mode, recirculation, and temperature control actuators provides positive positioning without the complexity of feedback from position sensors. The A/C - Heater Control Module knows the number of operating actuator revolutions required for full door travel as well as the number of actuator commutator pulses per revolution. Using these parameters, the A/C - Heater Control Module runs the actuator for the number of commutator pulses that correspond to the desired door position. To maintain accuracy, the system recalibrates itself periodically at known zero and full travel conditions.

On Three-Zone systems, the Rear A/C-Heater Control:

controls rear blower motor operating speed. The three blower speeds are Low, Med, and High.
provides desired rear blend and mode door position input to the A/C-Heater Control Module.

The Single-Zone HVAC system uses:

one, two-wire electronic blend door actuator.
one, two-wire electronic mode door actuator.
one, two-wire electronic recirculation door actuator.

The Dual-Zone HVAC system uses:

two, two-wire electronic blend door actuators.
one, two-wire electronic mode door actuator.
one, two-wire electronic recirculation door actuator.

The Three-Zone HVAC system uses:

two front, two-wire electronic blend door actuators.
one front, two-wire electronic mode door actuator.
one, two-wire electronic recirculation door actuator.
one rear, two-wire electronic blend door actuator.
one rear, two-wire electronic mode door actuator.

System Relays

The Integrated Power Module (IPM) houses and provides power to the A/C Clutch Relay, Front Blower Motor Relay, and Rear Blower Motor Relay.