System Revisions

The 2004 RG MTC system remains carryover from 2003. Revisions to the 2004 RS MTC system include:

• All new 0900 version software.
  CAUTION: Manual Temperature Control (MTC) Modules in 2001 and 2002 RS/RG vehicles use 0614 and 0700 version software. MTC Modules in 2003 RS/RG and 2004 RG vehicles use 0802 version software. MTC Modules in 2004 RS vehicles use 0900 version software and have new control features. Do NOT install a MTC Module with 0614 or 0700 version software in a 2003 or 2004 RS/RG vehicle. Do NOT install a MTC Module with 0802 version software in a 2004 RS vehicle. Do not install a MTC Module with 0900 version software in a 2001, 2002, or 2003 model year RS/RG vehicle or in a 2004 RG vehicle. Use the DRBIII® to verify which version software the MTC Module is using by selecting Body Systems, HVAC, and then selecting Module Display. Failure to follow these instructions can result in either improper or failed HVAC system operation.
• changing the system on/off switch function to an intermittent rear wiper and rear washer control function.
• adding the system on/off function to the blower control switch.
• changing the number of blower speed settings from five to four.
• eliminating the odor control programming which allowed a small amount of fresh air to enter the cabin while in recirculation mode.
• moving the evaporator temperature sensor from the expansion valve to the top of the HVAC housing near the evaporator.