Circuit Description
The dash integration module (DIM) monitors the refrigerant temperature through the A/C refrigerant low temperature sensor. When the refrigerant is cold, the sensor resistance and signal voltage are high. When the refrigerant is warm, the sensor resistance and signal voltage are low. The DIM will not request A/C compressor clutch engagement when the refrigerant temperature is low enough to cause the A/C evaporator core to freeze.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1531 Air Conditioning A/C Evaporator Temperature Sensor Circuit
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The DIM detects the signal circuit is less than 127°C (261°F) or greater than -36°C (-34°F).
Action Taken When the DTC Sets
| • | A default value will be used by the DIM. |
| • | The A/C compressor clutch will not engage. |
Conditions for Clearing the DTC
| • | The DTC will become history if the DIM no longer detects a failure. |
| • | The history DTC will clear after 40 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
Test the following conditions:
| • | Visually inspect the sensor for contamination or damage. |
| • | Inspect for the following that may affect the sensors accuracy. |
| - | A malfunction within the refrigerant system causing low pressure. |
| - | Visually inspect the A/C components and lines for damage. |
| • | If condition not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for the proper operation of the circuit in the high voltage range.
-
This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
-
Perform the recalibration procedure for the dash integration module.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the scan tool indicate that the Evaporator Temp. parameter is within the specified range? | -36°C to 127°C (-34°F to 261°F) | Go to Diagnostic Aids | Go to Step 3 |
Does the scan tool indicate that the Evaporator Temp. parameter is less than the specified value? | -36°C (-34°F) | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the Evaporator Temp. parameter is greater than the specified value? | 127°C (261°F) | Go to Step 8 | Go to Step 6 | |
5 | Test the signal circuit of the A/C refrigerant low temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
6 | Test the signal circuit of the A/C refrigerant low temperature sensor or a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 |
7 | Test the low reference circuit of the A/C refrigerant low temperature sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the A/C refrigerant low temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the dash integration module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the A/C refrigerant low temperature sensor. Refer to Air Conditioning (A/C) Refrigerant Low Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
Replace the dash integration module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- | |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
