Circuit Description
A semiconductor which resistance is noticeably changed as the change of temperature. When the refrigerant temperature of the evaporator drops to 5°C (41°F) and below, the evaporator cores get stuck with frost or ice, reducing the airflow, lowering the cooling capacity. The thermistor is a sensor which is used to prevent from frosting or icing. The thermistor is installed on the evaporator.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0538 A/C Evaporator Temperature Sensor High
Conditions for Running the DTC
| • | Engine is running. |
| • | A/C switch is ON. |
| • | Engine coolant temperature (ECT) is higher than 39.75°C (103.55°F). |
| • | A/C relay is ON for more than 131 seconds. |
Conditions for Setting the DTC
Evaporator temperature sensor signal is higher than 4.9 V (0.8L) or 4.98 V (1.0L).
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored Failure Records buffers. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 warm-up cycles without a fault. |
| • | DTC(s) can be cleared by using the scan tool. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is the resistance within the specified value? | 0ohms | Go to Step 7 | Go to Step 3 |
3 |
Did you find the problem? | -- | Go to Step 4 | Go to Step 5 |
4 | Repair the wire or the connector between the terminal 46 (0.8L)/49 (1.0L) of ECM and A/C compressor relay terminal 2. Is the repair complete? | -- | Go to Step 9 | -- |
5 |
Did you find the problem? | -- | Go to Step 6 | Go to Step 8 |
6 | Repair the wire or the connector between the ECM wiring connector terminal 46 (0.8L)/49 (1.0L) and evaporator temperature sensor terminal 2. Is the repair complete? | -- | Go to Step 9 | -- |
7 | Replace the evaporator temperature sensor. Is the replacement complete? | -- | Go to Step 9 | -- |
8 | Replace the ECM. Is the repair complete? | -- | Go to Step 9 | -- |
9 |
Does the scan tool indicate that this diagnostic has run and passed? | -- | Go to Step 10 | Go to Step 2 |
10 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | -- | |
