Customer Concern: No heat and code 23 in the Automatic Temperature Control (ATC) system. Tests/Procedures: 1. Check for voltage across the driver wires (Brown/White wire and Dark Blue/Red wire) at the blend air door actuator while running a self-diagnostic test. To run self-diagnostics, press and hold the floor, mix, and defrost buttons for 3-5 seconds.
2. If at least 10 volts when going through the diagnostic test, but no change in temperature, the actuator is faulty. Potential Causes: Blend Air Door Actuator Calibration Wiring
Tech Tips: Code 23 is for the blend air door actuator. Diagnostic Codes: 23