Code
U0164
Generic
U — Network/User
Lost Communication With HVAC Control Module
Views:
UK: 61
EN: 91
RU: 65
AI status
Completed
Completed
100%
Causes
- HVAC control module fault (internal failure)
- Open, short or high resistance in CAN/LIN communication wiring
- Corroded or loose connector pins at the HVAC module
- Blown fuse or loss of module power or ground
- CAN bus wiring short to battery or ground, or missing termination
- Another module pulling down the bus or creating network errors
Symptoms
- HVAC/climate controls unresponsive or inoperative
- Incorrect or absent HVAC display information
- Loss of automatic climate functions (AUTO, temperature control)
- Related dash indicators or messages ("Service HVAC", "Check Climate")
- Other modules reporting network errors or degraded operation
- Codes for multiple modules or multiple lost-communication U-codes
What to check
- Retrieve freeze frame and all stored codes from all modules; note related U-codes.
- Scan network for presence of HVAC module (module list or address) with scan tool.
- Verify HVAC module fuse(s) are good and ignition power present.
- Check module ground(s) for low resistance to chassis.
- Visually inspect HVAC module connector and wiring harness for damage, corrosion, or pin push-out.
- Measure CAN_H and CAN_L voltages at the HVAC connector with key ON, engine OFF.
Signal parameters
- CAN_H idle voltage ≈ 2.5 V (recessive), CAN_L idle voltage ≈ 2.5 V; dominant state: CAN_H ≈ 3.5 V and CAN_L ≈ 1.5 V
- Differential voltage during frames ≈ 1.5–2.5 V when dominant
- Bus termination resistance ≈ 60 Ω (two 120 Ω terminators in parallel)
- Message frequency and ID for HVAC module (vehicle-specific; typically periodic status frames 1–10 Hz)
- Bus error counters and error frames (if available via scan tool)
Diagnostic algorithm
- Verify code and gather data: Read U0164 and any related U-codes. Note whether code is current or intermittent.
- Check power & ground: With key ON, verify HVAC module power feeds and ground(s) at the module connector (use a DVOM). Replace blown fuses and repair poor grounds before further tests.
- Verify presence on bus: Use a scan tool to list modules. If the HVAC module does not appear, test communications at the HVAC connector.
- Measure bus voltages: Measure CAN_H and CAN_L at HVAC connector with ignition ON and compare to expected levels. Abnormal voltages suggest short/opens or termination issues.
- Check termination & resistance: With ignition OFF, measure resistance between CAN_H and CAN_L at two points; expect ~60 Ω. Open or very low resistance indicates termination problem or short.
- Observe live traffic: Use an oscilloscope or CAN bus analyzer to view waveform quality and ensure other modules are transmitting. Identify whether the HVAC module ever transmits or if messages are corrupted.
- Isolate wiring: If bus looks healthy away from HVAC, disconnect HVAC module and inspect connector for corrosion or bent pins. Perform backprobe/wiggle tests while monitoring communication for intermittent faults.
- Repair wiring/connectors: Repair any damaged wires, pins, or grounds. Use proper crimp/solder and sealed connectors; protect repairs from moisture.
- Module verification: If wiring and bus operation are verified good and HVAC still won’t respond, consider replacing or bench-testing the HVAC module per manufacturer procedure.
- Clear codes & retest: After repairs, clear codes, verify HVAC returns on network, check climate functionality, and perform a road or soak test to ensure issue is resolved and code does not return.
Likely causes
- Blown or loose fuse for HVAC module power/ignition feed
- Bad ground at HVAC module or shared ground point
- Damaged HVAC module connector (corrosion bent pins)
- Broken or shorted CAN_H/CAN_L feed to HVAC module
- HVAC module internal failure
Fault status
Status
Lost Communication With HVAC Control Module — HVAC module not responding on vehicle communication bus (CAN/LIN).
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
U0164
HYUNDAI
U — Network/User
Lost Communication With HVAC Control Module | Lost Communication with HVAC Control Module
Views:
UK: 42
EN: 82
RU: 58
AI status
Completed
Completed
100%
Causes
- HVAC control module fault (internal failure)
- Open, short or high resistance in CAN/LIN communication wiring
- Corroded or loose connector pins at the HVAC module
- Blown fuse or loss of module power or ground
- CAN bus wiring short to battery or ground, or missing termination
- Another module pulling down the bus or creating network errors
Symptoms
- HVAC/climate controls unresponsive or inoperative
- Incorrect or absent HVAC display information
- Loss of automatic climate functions (AUTO, temperature control)
- Related dash indicators or messages ("Service HVAC", "Check Climate")
- Other modules reporting network errors or degraded operation
- Codes for multiple modules or multiple lost-communication U-codes
What to check
- Retrieve freeze frame and all stored codes from all modules; note related U-codes.
- Scan network for presence of HVAC module (module list or address) with scan tool.
- Verify HVAC module fuse(s) are good and ignition power present.
- Check module ground(s) for low resistance to chassis.
- Visually inspect HVAC module connector and wiring harness for damage, corrosion, or pin push-out.
- Measure CAN_H and CAN_L voltages at the HVAC connector with key ON, engine OFF.
Signal parameters
- CAN_H idle voltage ≈ 2.5 V (recessive), CAN_L idle voltage ≈ 2.5 V; dominant state: CAN_H ≈ 3.5 V and CAN_L ≈ 1.5 V
- Differential voltage during frames ≈ 1.5–2.5 V when dominant
- Bus termination resistance ≈ 60 Ω (two 120 Ω terminators in parallel)
- Message frequency and ID for HVAC module (vehicle-specific; typically periodic status frames 1–10 Hz)
- Bus error counters and error frames (if available via scan tool)
Diagnostic algorithm
- Verify code and gather data: Read U0164 and any related U-codes. Note whether code is current or intermittent.
- Check power & ground: With key ON, verify HVAC module power feeds and ground(s) at the module connector (use a DVOM). Replace blown fuses and repair poor grounds before further tests.
- Verify presence on bus: Use a scan tool to list modules. If the HVAC module does not appear, test communications at the HVAC connector.
- Measure bus voltages: Measure CAN_H and CAN_L at HVAC connector with ignition ON and compare to expected levels. Abnormal voltages suggest short/opens or termination issues.
- Check termination & resistance: With ignition OFF, measure resistance between CAN_H and CAN_L at two points; expect ~60 Ω. Open or very low resistance indicates termination problem or short.
- Observe live traffic: Use an oscilloscope or CAN bus analyzer to view waveform quality and ensure other modules are transmitting. Identify whether the HVAC module ever transmits or if messages are corrupted.
- Isolate wiring: If bus looks healthy away from HVAC, disconnect HVAC module and inspect connector for corrosion or bent pins. Perform backprobe/wiggle tests while monitoring communication for intermittent faults.
- Repair wiring/connectors: Repair any damaged wires, pins, or grounds. Use proper crimp/solder and sealed connectors; protect repairs from moisture.
- Module verification: If wiring and bus operation are verified good and HVAC still won’t respond, consider replacing or bench-testing the HVAC module per manufacturer procedure.
- Clear codes & retest: After repairs, clear codes, verify HVAC returns on network, check climate functionality, and perform a road or soak test to ensure issue is resolved and code does not return.
Likely causes
- Blown or loose fuse for HVAC module power/ignition feed
- Bad ground at HVAC module or shared ground point
- Damaged HVAC module connector (corrosion bent pins)
- Broken or shorted CAN_H/CAN_L feed to HVAC module
- HVAC module internal failure
Fault status
Status
Lost Communication With HVAC Control Module — HVAC module not responding on vehicle communication bus (CAN/LIN).
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Was this AI description helpful?
Your feedback helps improve AI descriptions.
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Code
U0164
LAND ROVER
U — Network/User
Lost communication with the control module of ventilation and heating of the air conditioning
Views:
UK: 37
EN: 102
RU: 44
AI status
Completed
Completed
100%
Causes
- HVAC control module fault (internal failure)
- Open, short or high resistance in CAN/LIN communication wiring
- Corroded or loose connector pins at the HVAC module
- Blown fuse or loss of module power or ground
- CAN bus wiring short to battery or ground, or missing termination
- Another module pulling down the bus or creating network errors
Symptoms
- HVAC/climate controls unresponsive or inoperative
- Incorrect or absent HVAC display information
- Loss of automatic climate functions (AUTO, temperature control)
- Related dash indicators or messages ("Service HVAC", "Check Climate")
- Other modules reporting network errors or degraded operation
- Codes for multiple modules or multiple lost-communication U-codes
What to check
- Retrieve freeze frame and all stored codes from all modules; note related U-codes.
- Scan network for presence of HVAC module (module list or address) with scan tool.
- Verify HVAC module fuse(s) are good and ignition power present.
- Check module ground(s) for low resistance to chassis.
- Visually inspect HVAC module connector and wiring harness for damage, corrosion, or pin push-out.
- Measure CAN_H and CAN_L voltages at the HVAC connector with key ON, engine OFF.
Signal parameters
- CAN_H idle voltage ≈ 2.5 V (recessive), CAN_L idle voltage ≈ 2.5 V; dominant state: CAN_H ≈ 3.5 V and CAN_L ≈ 1.5 V
- Differential voltage during frames ≈ 1.5–2.5 V when dominant
- Bus termination resistance ≈ 60 Ω (two 120 Ω terminators in parallel)
- Message frequency and ID for HVAC module (vehicle-specific; typically periodic status frames 1–10 Hz)
- Bus error counters and error frames (if available via scan tool)
Diagnostic algorithm
- Verify code and gather data: Read U0164 and any related U-codes. Note whether code is current or intermittent.
- Check power & ground: With key ON, verify HVAC module power feeds and ground(s) at the module connector (use a DVOM). Replace blown fuses and repair poor grounds before further tests.
- Verify presence on bus: Use a scan tool to list modules. If the HVAC module does not appear, test communications at the HVAC connector.
- Measure bus voltages: Measure CAN_H and CAN_L at HVAC connector with ignition ON and compare to expected levels. Abnormal voltages suggest short/opens or termination issues.
- Check termination & resistance: With ignition OFF, measure resistance between CAN_H and CAN_L at two points; expect ~60 Ω. Open or very low resistance indicates termination problem or short.
- Observe live traffic: Use an oscilloscope or CAN bus analyzer to view waveform quality and ensure other modules are transmitting. Identify whether the HVAC module ever transmits or if messages are corrupted.
- Isolate wiring: If bus looks healthy away from HVAC, disconnect HVAC module and inspect connector for corrosion or bent pins. Perform backprobe/wiggle tests while monitoring communication for intermittent faults.
- Repair wiring/connectors: Repair any damaged wires, pins, or grounds. Use proper crimp/solder and sealed connectors; protect repairs from moisture.
- Module verification: If wiring and bus operation are verified good and HVAC still won’t respond, consider replacing or bench-testing the HVAC module per manufacturer procedure.
- Clear codes & retest: After repairs, clear codes, verify HVAC returns on network, check climate functionality, and perform a road or soak test to ensure issue is resolved and code does not return.
Likely causes
- Blown or loose fuse for HVAC module power/ignition feed
- Bad ground at HVAC module or shared ground point
- Damaged HVAC module connector (corrosion bent pins)
- Broken or shorted CAN_H/CAN_L feed to HVAC module
- HVAC module internal failure
Fault status
Status
Lost Communication With HVAC Control Module — HVAC module not responding on vehicle communication bus (CAN/LIN).
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
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0
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