DESCRIPTION
| WARNING | To avoid injury from accidental air bag deployment, read and carefully follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. |
| CAUTION | When battery is disconnected, radio will go into anti-theft protection mode. Obtain radio anti-theft protection code from owner prior to servicing vehicle. |
This vehicle is equipped with a Variable Displacement Orifice Tube (VDOT) system that can match A/C demands under all conditions without cycling. The air inlet assembly provides outside or inside air to blower depending on mode selected. The inlet air is varied by an actuator which is controlled by the A/C-heater unit. If a fault occurs, a trouble code is stored in memory inside the A/C-heater unit. The Heater Ventilation Air Conditioning (HVAC) controls are divided into 3 primary areas: heater mode, A/C mode and A/C cycle mode.
The Instrument Panel Integration Module (IPM) reads information from ambient air temperature sensor, inside air temperature sensor, sunload sensor, lower left/right air temperature sensors and upper left/right temperature sensors. The Powertrain Control Module (PCM) reads inputs from engine coolant temperature sensor and A/C pressure sensor. The Dash Integration Module (DIM) reads A/C refrigerant low temperature and engine coolant temperature sensor inputs from PCM. The DIM will request A/C operation from PCM, if parameters are within normal operating limits.
In heater mode, the heater supplies heat to interior of vehicle. The vehicle is equipped with a dual-zone control system, allowing operator and passenger separate controls and can adjust the level of heat by either the left or right air temperature switch, located on the A/C-heater control unit, to any setting regardless of the HVAC mode setting. The driver and passenger can independently select temperatures from full hot, 90°F (32°C), to cold, 60°F (16°C).
The air conditioning system provides cool air and removes humidity from the interior of the vehicle. The A/C system is active when the A/C-heater control unit is in A/C or FRONT DEFROST mode. The A/C system can operate regardless of the temperature setting, as long as ambient (outside) temperature is above 37°F (3°C). If driver tries to turn off the A/C system while in FRONT DEFROST mode, the A/C OFF text on the vacuum florescent display will flash, indicating that this is not allowed. If the A/C compressor is turned off due to low ambient (outside) temperatures, the compressor will not be activated until temperature reaches 42°F (6°C).
Since the A/C system used on this vehicle does not cycle, the system uses a high-pressure switch to protect the A/C system from excessive pressure. The high-pressure switch will open electrical circuit to the A/C compressor clutch if the refrigerant pressure becomes excessive. When the high and low sides pressures of the A/C system equalize, the high-pressure switch will close and complete the electrical circuit to the A/C compressor clutch. The A/C system is also protected with the use of a mechanical high-pressure relief valve. If the high-pressure switch failed or if the system becomes restricted and refrigerant pressure continues to rise, the high-pressure relief valve will open and release refrigerant from the system.