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DTC codes / U06xx · Network communication / U062B

U062BLost Communication With A/C Refrigerant Distribution Valve Actuator B

This code means the module that controls the air conditioning system has lost the communication signal it expects from the refrigerant distribution valve actuator B, which is the small electric motor that directs refrigerant flow between the cabin evaporator and other circuits. The control module sets U062B when it stops receiving valid messages or feedback from that actuator over the vehicle's communication network, so it can no longer confirm the valve is responding to commands.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • The air conditioning may blow warm air on one side or stop cooling entirely because the valve cannot be positioned.
  • A warning light or climate control message may appear, often with the A/C button flashing or disabled.
  • The blower may run normally while vent temperature stays inconsistent or stuck at one setting.
  • You may hear no change in refrigerant flow or valve movement when switching between A/C modes.
  • Often no symptoms besides the warning light, especially if the fault is intermittent and the valve still parks correctly.
  • Other climate functions such as defrost or rear A/C may behave erratically if the network fault affects shared communication.

Common causes, most likely first

  1. A damaged or corroded electrical connector at the refrigerant distribution valve actuator, allowing water or vibration to interrupt the signal.
  2. A chafed, pinched, or open wire in the communication circuit between the actuator and the control module.
  3. A failed refrigerant distribution valve actuator motor or its internal position sensor, which stops responding to network messages.
  4. Low or unstable battery voltage, or a weak ground at the actuator or control module, causing communication dropouts.
  5. A software or calibration issue in the climate control module that misinterprets actuator feedback.
  6. A faulty climate control module or body control module that cannot send or receive messages on the communication bus.
  7. Network bus faults elsewhere on the vehicle that disrupt messages to the climate module, even though the actuator itself is fine.

How to diagnose and fix it

  1. Scan all modules for stored and pending codes, record freeze-frame data, and clear codes to see whether U062B returns immediately.
  2. Inspect the actuator connector and harness for corrosion, pushed pins, water intrusion, and chafing, then clean and reseat the connector.
  3. Measure battery voltage and check the actuator ground and power supply under load to rule out low voltage or a bad ground.
  4. Back-probe the communication circuit at the actuator and at the control module to check for continuity, shorts, and correct bus voltage.
  5. Command the refrigerant distribution valve actuator with a scan tool and watch for position feedback to confirm whether the actuator responds.
  6. If the actuator does not respond but wiring and power are good, replace the actuator and perform any required calibration or relearn procedure.
  7. If communication is still lost after actuator replacement, diagnose the climate control module and the network bus for faults that block messages.

What a lost actuator message really means

  • A U062B is a communication code, not a direct valve failure code, so the actuator may be mechanically fine while a wiring or module fault blocks its messages.
  • Intermittent codes often trace to a connector that fills with water or a harness that rubs near the valve, so wiggle-testing the harness while watching live data is more useful than replacing parts.
  • Low battery voltage or a weak ground can set this code on vehicles that sit for long periods, and the code may never return after a full charge and ground service.
  • Some climate control modules require a calibration or relearn after actuator replacement, and skipping that step can leave the new actuator unrecognized and the code resetting.
  • A fault on the communication bus elsewhere in the vehicle can prevent the climate module from hearing the actuator, so always check whether other modules store communication codes at the same time.

Can I keep driving with U062B?

You can usually drive the vehicle, but the air conditioning may not cool properly and defrost performance can suffer in humid weather. Avoid long trips in hot conditions until the fault is repaired, and do not ignore repeated warning lights because a communication fault can affect other climate functions.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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