G5 COMPARE THE PCM (POWERTRAIN CONTROL MODULE) INTAKE AIR TEMPERATURE (IAT) PID (PARAMETER IDENTIFICATION) AND THE OTHER TEMPERATURE SENSOR READINGS TO THE PCM (POWERTRAIN CONTROL MODULE) AMBIENT AIR TEMPERATURE (AAT) PID (PARAMETER IDENTIFICATION)
NOTE: Compare multiple engine sensor readings to the ambient temperature to determine sensors are reading correctly. A faulty sensor can cause the PCM to disable the A/C with or without a DTC.
Allow the vehicle exterior and interior to stabilize to ambient temperature. This can take a soak period of at least 6 hours. Using a diagnostic scan tool, view PCM Parameter Identifications (PIDs). Monitor the CHT, ECT, IAT, MAPT, and AAT Parameter Identifications (PIDs) (as applicable).
Are the temperature values similar (typically within 18ºC (32.4ºF)?
Yes | GO to G6 | |
|---|---|---|
No | DIAGNOSE the suspect temperature sensor. REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual, Section 3 Symptom Charts. | |
G6 COMPARE THE EVAPORATOR TEMPERATURE SENSOR TO THE PCM (POWERTRAIN CONTROL MODULE) AMBIENT AIR TEMPERATURE (AAT) PID (PARAMETER IDENTIFICATION)
Ignition OFF. Disconnect Evaporator temperature sensor C296. Measure:
Click to display connectors
Positive Lead | Measurement / Action | Negative Lead |
|---|---|---|
C296-1 (component side) | C296-2 (component side) |
Compare the resistance values to the table below:
Ambient Temperature °F (°C) | Resistance ohms |
-39.9°F (-40°C) | 98,625 - 103,275 ohms |
-4.0°F (-20°C) | 28,640 - 29,600 ohms |
32.0°F (°C) | 9695 - 9895 ohms |
68.0°F (20°C) | 3675 - 3810 ohms |
77.0°F (25°C) | 2950 - 3050 ohms |
86.0°F (30°C) | 2370 - 2565 ohms |
103.9°F (40°C) | 1565 - 1635 ohms |
Ignition ON. Using a diagnostic scan tool, view PCM Parameter Identifications (PIDs). Monitor the AAT PID.
Is the resistance within the specified values for the temperatures?
Original table alignment retained · Scroll horizontally if needed
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.