Pinpoint Test D: DTC B2950 - Air Conditioning System Fault, DTC P0535 - A/C Evaporator Temperature Sensor Circuit Failure
Climate Control System
Pinpoint Tests
Pinpoint Test D: DTC B2950 - Air Conditioning System Fault, DTC P0535 - A/C Evaporator Temperature Sensor Circuit Failure
Refer to Wiring Diagram Set 55 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
When the High Voltage Traction Battery (HVTB) compartment approaches its upper temperature limit, the Traction Battery Control Module (TBCM) requests battery cooling from the PCM. The PCM returns a signal to the TBCM allowing battery cooling under the correct conditions. The TBCM then monitors the auxiliary evaporator for a temperature drop.
The TBCM sends a voltage signal through circuit VYB07 (GN/WH) to the auxiliary evaporator thermistor. The signal is returned from the auxiliary evaporator thermistor through circuit RYB07 (GY/YE) to the TBCM.
- DTC B2950 Air Conditioning System Fault - The refrigerant distribution valve temperature has not been reduced by more than 2°C (4°F) since the valve is opened.
- DTC P0535 A/C Evaporator Temperature Sensor Circuit Failure - The Thermostatic Expansion Valve (TXV) temperature is less than -40°C (-40°F) or greater than 119°C (246°F).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Base A/C system
- Auxiliary evaporator thermistor
- TBCM
PINPOINT TEST D: DTC B2950 - AIR CONDITIONING SYSTEM FAULT, DTC P0535 - A/C EVAPORATOR TEMPERATURE SENSOR CIRCUIT FAILURE
NOTE: Repair all other DTCs before proceeding with this pinpoint test.
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D1 CHECK THE BASE A/C SYSTEM FOR CORRECT OPERATION
- Test the base A/C system.
- Does the base A/C system operate correctly?
Yes
GO to D2.
No
REPAIR the base A/C system.
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D2 CHECK THE AUXILIARY EVAPORATOR THERMISTOR CIRCUITS
- Ignition OFF.
- Disconnect: Auxiliary Evaporator Thermistor C4228.
- Ignition ON.
- Measure the voltage between auxiliary evaporator thermistor C4228-1, circuit RYB07 (GY/YE), harness side and auxiliary evaporator thermistor C4228-2, circuit VYB07 (GN/WH), harness side.
- Is the voltage between 4.7 and 5.3 volts?
Yes
GO to D3.
No
GO to D4.
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D3 CHECK THE AUXILIARY EVAPORATOR THERMISTOR
- Ignition OFF.
- Disconnect: TBCM C4227a.
- Connect: Auxiliary Evaporator Thermistor C4228.
- Measure the resistance between TBCM C4227a-21, circuit VYB07 (GN/WH), harness side and TBCM C4227a-25, circuit RYB07 (GY/YE), harness side.
- Is the resistance within the expected value range?
Yes
GO to D7.
No
INSTALL a new auxiliary evaporator thermistor. REPEAT the self-test. TEST the system for normal operation.
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D4 CHECK THE AUXILIARY EVAPORATOR THERMISTOR CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Connect: Auxiliary Evaporator Thermistor C4228.
- Disconnect: TBCM C4227a.
- Ignition ON.
- Measure the voltage between TBCM C4227a-21, circuit VYB07 (GN/WH), harness side and ground.
- Is any voltage present?
Yes
GO to D5.
No
GO to D6.
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D5 CHECK CIRCUITS VYB07 (GN/WH) AND RYB07 (GY/YE) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Evaporator Thermistor C4228.
- Ignition ON.
- Measure the voltage between TBCM C4227a-21, circuit VYB07 (GN/WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit VYB07 (GN/WH). REPEAT the self-test. TEST the system for normal operation.
No
REPAIR circuit RYB07 (GY/YE). REPEAT the self-test. TEST the system for normal operation.
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D6 CHECK CIRCUITS VYB07 (GN/WH) AND RYB07 (GY/YE) FOR AN OPEN
- Ignition OFF.
- Disconnect: Auxiliary Evaporator Thermistor C4228.
- Measure the resistance between the TBCM connector, harness side and auxiliary evaporator thermistor connector, body harness side using the following chart.
- Are the resistances less than 5 ohms?
Yes
CONNECT the auxiliary evaporator thermistor C4228. GO to D7.
No
REPAIR the circuit(s) in question. REPEAT the self-test. TEST the system for normal operation.
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D7 CHECK THE AUXILIARY EVAPORATOR THERMISTOR CIRCUITS FOR A SHORT TO GROUND
- Measure the resistance between TBCM C4227a-21, circuit VYB07 (GN/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to D9.
No
GO to D8.
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D8 CHECK CIRCUITS VYB07 (GN/WH) AND RYB07 (GY/YE) FOR A SHORT TO GROUND
- Disconnect: Auxiliary Evaporator Thermistor C4228.
- Measure the resistance between TBCM C4227a-21, circuit VYB07 (GN/WH), harness side and ground; and between TBCM C4227a-25, circuit RYB07 (GY/YE), harness side and ground.
- Are the resistances greater than 10,000 ohms?
Yes
INSTALL a new auxiliary evaporator thermistor. REPEAT the self-test. TEST the system for normal operation.
No
REPAIR the circuit(s) in question. REPEAT the self-test. TEST the system for normal operation.
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D9 CHECK FOR CORRECT TBCM OPERATION
- Disconnect all the TBCM connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all the TBCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new TBCM. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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