ATC Module

Front and rear Heater, Ventilation and Air Conditioning (HVAC) functions are electronically controlled by Automatic Temperature Control (ATC) module. ATC module is integral of ATC control panel located in center fascia panel of instrument panel. ATC module utilizes integrated circuitry and information carried through Programmable Communications Interface (PCI) data bus network to monitor various sensor and switch inputs. In response to various inputs, ATC module can electronically control functions and features of each climate zone. The various inputs to ATC module are:

• A/C System Information
  
  ATC module will send a command message for evaporator temperature, fan blower relay status, evaporator sensor failure, rear window defogger relay and A/C compressor request. ATC module will then receive inputs to verify command message was received and command was performed.
• Ambient Temperature
  
  ATC module monitors ambient temperature from Compass Mini Trip Computer (CMTC). ATC module converts this CMTC input to degrees Fahrenheit for English, or degrees Centigrade for Metric display settings.
• Coolant Temperature
  
  ATC module monitors engine coolant temperature from Powertrain Control Module (PCM) input signal. ATC module converts PCM electronic input signal it into degrees Fahrenheit/Metric values.
• Dimming
  
  ATC module monitors display dimming status of Body Control Module (BCM) to determine proper brightness level for ATC control panel Vacuum Fluorescent (VF) display.
• Door Ajar Status
  
  ATC module monitors door ajar information from Body Control Module (BCM) to determine if in-car temperature should be maintained or suspended.
• English/Metric
  
  ATC module monitors information broadcast by Compass Mini Trip Computer (CMTC) and other modules. ATC module converts inputs and displays converted values on ATC control panel or rear control panel accordingly.
• Refrigerant Pressure
  
  ATC module monitors barometric pressure, intake air temperature, A/C high side refrigerant pressure and methanol content broadcast by Powertrain Control Module (PCM). ATC module converts these inputs to A/C system refrigerant pressure value.
• Vehicle Identification Number (VIN)
  
  ATC module monitors and stores the last 8 characters of VIN broadcast by Powertrain Control Module (PCM). ATC module compares this information with information stored in memory every ignition cycle. If information changes (replacing PCM), or if the information is different than stored information, a new VIN will be stored over old number, and calibration test for actuators shall be automatically initiated. ATC system functions may be limited when this has occurred.
• Vehicle Odometer
  
  ATC module monitors vehicle odometer information input from Body Control Module (BCM). If calibration test or cool down test have failed, Vacuum Florescent (VF) display icons of ATC control panel will flash continuously. Vehicle odometer input will prevent the continuous flashing of VF display icons when a fault has been detected. Flashing of display icons will cease after vehicle is driven more than 3 miles.
• Vehicle Speed/Engine RPM
  
  ATC module monitors engine RPM, vehicle speed and Manifold Absolute Pressure (MAP) sensor information from Powertrain Control Module (PCM).