🚨 Diagnostic Profile
Vehicle Make: Chrysler
Fault Description: A/C Evaporator Temperature Sensor Circuit High Voltage. The A/C evaporator temperature sensor (typically an NTC thermistor used by the HVAC control module to monitor evaporator core temperature and prevent evaporator icing) is reporting a signal voltage above the expected operating range, which generally indicates an open circuit, a disconnected connector, or a failed sensor.
🚨 Repair Difficulty Tier
Tier: [DIY / Beginner]
Most causes of this code involve accessible wiring, connector inspection, or sensor replacement located at the evaporator housing. Sensor access may require removing the glovebox or cabin air filter housing, which is generally within the capability of a patient DIY technician. Diagnosis of wiring faults between the sensor and the HVAC control module may require a multimeter and wiring diagram, raising the tier to [Intermediate] on some platforms.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
- Verify battery voltage and confirm no other HVAC or body control module codes are stored, as low system voltage or a BCM communication fault can set false temperature sensor codes.
- Inspect the A/C evaporator temperature sensor connector at the evaporator housing for corrosion, bent pins, moisture intrusion, or loose seating.
- Inspect the sensor wiring harness for chafing, pinching, or heat damage along its route to the HVAC control module, paying close attention to areas near the blower motor resistor and firewall grommet.
- Locate the sensor and confirm its physical mounting: on most Chrysler platforms, the evaporator temperature sensor is a probe-style thermistor inserted directly into the evaporator core fins, accessed behind the glovebox or lower dash panel after removing the HVAC housing cover or cabin air filter assembly.
- Clear the stored code using a capable scan tool and perform a key-cycle or short drive cycle with the A/C compressor engaged to determine whether the fault resets.
Step 2: Diagnostic Verification
- Disconnect the sensor and measure resistance across the sensor terminals with a digital multimeter. NTC thermistors used in this application typically read high resistance (several thousand ohms) at cold ambient temperatures and progressively lower resistance as temperature rises; an open circuit (infinite resistance) or a reading wildly inconsistent with ambient cabin temperature confirms sensor failure.
- Check the reference voltage supplied by the HVAC control module at the harness-side connector (sensor disconnected) using a digital multimeter against a known good chassis ground; most Chrysler HVAC modules supply a low reference voltage (typically 5V or less) on this circuit.
- Perform a continuity and resistance check on the signal and ground circuits between the sensor connector and the HVAC control module using the appropriate factory wiring diagram for the exact model year to identify correct circuit and terminal numbering, since pin-outs vary by platform and cannot be assumed without model-specific documentation.
- Check for shorts to voltage or open circuits by testing each conductor against ground with the ignition on and the sensor connector disconnected; a reading showing battery voltage or near-open resistance on the signal circuit indicates a chafed wire shorted to a powered circuit or a broken conductor consistent with a High Voltage code.
- Confirm whether the fault is in the sensor, the wiring, or the control module by substituting a known-good sensor or using a calibrated resistor decade box to simulate expected resistance values while monitoring the live PID/data stream on the scan tool.
Step 3: Resolution & Reset Process
- If the sensor reads out of specification or shows an open circuit, replace the A/C evaporator temperature sensor with an OEM or OEM-equivalent part matched to the exact model year and HVAC system configuration.
- If the wiring shows an open or high-resistance fault, repair the harness using solder-sealed splices and adhesive-lined heat-shrink insulation, or replace the affected wiring section per manufacturer-approved splicing procedures; avoid simple crimp-only butt connectors in this high-vibration, temperature-cycled area.
- If connector pins are corroded or damaged, clean with electrical contact cleaner and a terminal pick, or replace the terminals using manufacturer-approved pin extraction and crimping tools and procedures.
- Reconnect all components, verify secure seating with an audible click, and confirm harness routing is clear of the blower wheel, evaporator drain, and sharp sheet metal edges.
- Clear all stored DTCs with a scan tool and perform a HVAC system self-test or module re-initialization if supported by the platform, then verify live evaporator temperature readings track logically with blower speed and compressor cycling on the scan tool data stream.
- Perform a final road test with the A/C set to maximum cooling for at least 15-20 minutes to allow the evaporator to reach normal operating temperature and confirm the fault does not return.
📦 Parts, Labor, and Budget Estimates
Required Components/Software:
- A/C evaporator temperature sensor (OEM or OEM-equivalent, model-year specific part number required from dealer parts catalog or verified aftermarket cross-reference)
- Replacement connector pigtail or individual terminals, if corrosion or pin damage is found
- Wiring repair supplies: automotive-grade solder, adhesive-lined heat-shrink tubing, split loom or harness tape
- Digital multimeter capable of accurate low-voltage and resistance measurements
- OEM-level or enhanced aftermarket scan tool with bi-directional HVAC data stream access (e.g., capable of reading evaporator temperature PID and performing HVAC module resets)
- Manufacturer service information subscription or factory wiring diagram specific to the exact model year for correct circuit and pin identification
Average Component Price:
- Evaporator temperature sensor: approximately $25-$90 depending on platform and OEM vs. aftermarket sourcing
- Connector pigtail/terminal repair kit: approximately $15-$45
- Wiring repair supplies (solder, heat-shrink, loom): approximately $10-$25
- Diagnostic scan fee (if performed by a shop): approximately $100-$180 per hour, typically billed as a flat diagnostic charge of $90-$150
Estimated Labor Hours:
- Diagnostic verification (connector inspection, resistance/voltage testing, wiring checks): 0.5-1.5 hours
- Sensor access and replacement (glovebox/cabin air filter housing removal, sensor swap, reassembly): 0.7-1.5 hours depending on platform and HVAC housing design
- Wiring repair, if required (splice, terminal repair, harness re-routing): 0.5-1.2 additional hours
- Verification, code clearing, and road test: 0.3-0.5 hours
- Total estimated shop labor: approximately 1.5-3.5 hours, with typical shop labor rates ranging from $120-$180 per hour depending on region and dealer vs. independent shop