• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Ambient Air Temperature Sensor Signal | 2 | 1 | 1 | -- |
Ambient Air Temperature Low Reference | -- | 1 | 1 | -- |
1. Too hot in vehicle condition 2. Temperature display inaccurate |
The HVAC control module supplies the ambient air temperature sensor with a low reference circuit and signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.
Control Module References for scan tool information
Important: An instant OAT update must be performed by pressing the A/C and Recirc buttons at the same time after the system has been repaired to convert the A/C permission from out of range to normal.
⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module. |
⇒ | If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module. |
⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for HVAC control module replacement, setup and programming |