U0164 U0xxx · Network (U) Low severity
Lost Communication with HVAC Control Module
The climate control module is not responding. Usually a comfort problem rather than a drivability one — except on EVs where it manages battery thermal control.
Severity guidance: Low — usually no drivability impact, fix at the next service
Symptoms you will notice
- No heating or cooling control
- Climate display dead
- Blower on a default speed
Common causes
Ordered from most to least likely — start at the top.
- 1 HVAC module power fault
- 2 LIN or CAN fault
- 3 Failed module
- 4 Corroded connector
How to diagnose it
Cheapest and least invasive first — most of these codes are not a parts problem.
- ✓ Check HVAC fuses and the module connector.
- ✓ Determine whether it uses LIN or CAN and test accordingly.
- ✓ Inspect for water ingress near the HVAC housing.
- ✓ On EVs, check whether battery thermal management is affected.
Repair options
- Repair the power supply or wiring
- Replace the HVAC module
- Seal against water ingress
U0164 — frequently asked questions
Does it matter on an EV? +
Yes — the same module often controls battery cooling and heating, so a fault can affect charging speed and range.
Can I still demist the screen? +
Usually in a default mode. Enough for safety, but not comfortable.
Confirm the diagnosis before you buy parts
Send us the code, freeze-frame data and the vehicle — our engineers will tell you what to test first.