🚨 Diagnostic Profile
Vehicle Make: CHRYSLER
Description: A/C Low Side Temperature Sensor Fault. The low side (suction line) temperature sensor reports a reading outside its expected range to the HVAC or climate control module, which may trigger a fault code and affect A/C performance.
🚨 Repair Difficulty Tier
Tier: [Intermediate]
Sensor access and replacement are generally straightforward, but diagnosing whether the fault lies in the sensor, its wiring, the connector, or the control module requires electrical testing and familiarity with HVAC system operation. Refrigerant handling may be required if the sensor is serviced on a charged line.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
- Verify the stored DTC and freeze-frame data with a scan tool capable of reading the HVAC/climate control module (not just powertrain codes). Record the exact code, ambient temperature, and A/C request status at time of fault.
- Visually inspect the low side sensor connector for corrosion, bent pins, moisture intrusion, or a loose/unseated lock tab.
- Inspect the sensor harness for chafing, pinched sections, or heat damage. On most Chrysler/Dodge/Jeep platforms, the low side sensor is threaded into or clipped onto the suction line (accumulator outlet or evaporator outlet line) in the engine bay near the firewall or compressor suction port — trace the harness back to the HVAC-CM, BCM, or CCN connector depending on platform.
- Confirm the low side sensor mounting is secure, properly clipped to the line for full thermal contact, and the sensor body is free of oil residue indicating a refrigerant leak at the fitting.
- Check the A/C system refrigerant charge level and static/dynamic pressure readings against the underhood A/C label specification — low charge is a common cause of out-of-range low side temperature readings that mimic a sensor fault.
Step 2: Diagnostic Verification
- With the connector disconnected and key on (engine off), measure sensor reference voltage at the harness-side connector using a digital multimeter referenced to a known good chassis ground. Most Chrysler low side temp sensors are thermistor-type fed by a 5V reference circuit from the control module; confirm reference voltage is present and stable.
- Back-probe the signal circuit with the connector connected and compare the live voltage reading to the scan tool’s displayed low side temperature PID — the voltage should shift smoothly and proportionally as sensor temperature changes (verify by applying a heat source or cold spray to the sensor tip).
- With the connector disconnected, measure resistance across the sensor’s two terminals and compare to the manufacturer’s temperature-vs-resistance chart in the service information; most thermistor sensors read several thousand ohms at room temperature and decrease as temperature rises (NTC behavior).
- Check circuit continuity from the sensor connector back to the control module connector (HVAC-CM, BCM, or integrated CCN depending on model/year) with the module disconnected, confirming near-zero resistance on both the reference and signal wires.
- Test for shorts to ground and shorts to B+ on the signal circuit with the sensor disconnected and ignition on; any unexpected voltage or continuity to ground indicates a wiring fault rather than a sensor fault.
- After isolating and correcting any wiring issue, clear codes and monitor the live low side temperature PID against a calibrated reference thermometer at the suction line to confirm sensor accuracy within a reasonable tolerance (typically within a few degrees).
Step 3: Resolution & Reset Process
- Repair any damaged wiring using solder and adhesive-lined heat shrink or OEM-spec connector/pigtail kits — avoid crimp-only butt connectors in engine bay environments due to corrosion risk. Replace the low side temperature sensor if it fails resistance/temperature correlation or reference voltage testing.
- If the sensor is integrated into a charged line (common on many Chrysler minivan and Jeep/RAM applications), recover refrigerant per EPA 609 procedures using a certified recovery/recharge machine, replace the sensor and its O-ring/seal, evacuate the system to an appropriate vacuum level and hold time to confirm no leaks, then recharge to the exact weight specified on the underhood A/C label.
- Clear all stored DTCs across HVAC, BCM, and PCM modules with a scan tool and verify no immediate code reset occurs with A/C requested on.
- Run the A/C system through a full cool-down cycle at idle and at road speed, monitoring the low side temperature PID for smooth, logical tracking relative to compressor cycling and blend door operation.
- Rescan all modules after the test drive to confirm no active or pending fault codes remain and that the HVAC system is commanding compressor engagement and blend door position normally.
📦 Parts, Labor, and Budget Estimates
Required Components/Software:
- Low side (suction line) A/C temperature sensor — OEM or OE-equivalent thermistor sensor matched to the specific Chrysler/Dodge/Jeep/RAM platform and model year
- Connector pigtail or weather-pack harness repair kit, if wiring damage is found
- Refrigerant (R-134a or R-1234yf depending on model year) and PAG oil matched to system type, if the line is opened for sensor service
- Scan tool with full HVAC/climate control module bi-directional access (e.g., a professional-level scan tool such as a Snap-on, Autel, or OEM-level Chrysler diagnostic software such as wiTECH for full module-level diagnostics and DTC clearing)
Average Component Price:
- Low side temperature sensor: approximately $35–$120 (parts only), depending on platform and whether it is a standalone sensor or integrated into an accumulator/line assembly
- Harness or connector pigtail repair kit: approximately $20–$60
- Refrigerant and oil service (if system is opened): approximately $100–$250 depending on system capacity and refrigerant type (R-1234yf systems run notably higher than R-134a)
Estimated Labor Hours:
- Diagnosis and electrical verification (scan, visual inspection, voltage/resistance testing): approximately 0.5–1.5 hours
- Sensor replacement and A/C system service (recovery, sensor swap, evacuate/recharge if line is opened): approximately 0.8–2.0 hours depending on sensor accessibility and whether refrigerant recovery is required
- Post-repair verification, DTC clearing, and road test: approximately 0.3–0.5 hours
Estimated Total Out-the-Door Cost: Approximately $150–$450 for a straightforward sensor replacement with no refrigerant service, or $300–$650 if the sensor requires system recovery/recharge, depending on local labor rates and refrigerant type.