Lost Communication With HVAC Control Module
What it means
U0164 means a controller has lost communication with the HVAC control module — the unit that runs the heating, ventilation, and air-conditioning system. When it drops off the network, climate controls stop responding and you may lose A/C, heat, or fan control, but the engine, brakes, and steering are unaffected. It is usually caused by a wiring or connector fault, a lost power or ground feed, or a failed module.
Can I keep driving? Yes — this affects climate control only, so the car drives and stops normally; you may just lose automatic heating, A/C, or fan control until it's fixed.
Common symptoms
What you'll notice
- Climate control unresponsive or stuck on one setting
- No A/C, heat, fan-speed, or airflow control
- HVAC display or buttons dead or frozen
- The HVAC control module unresponsive to a scan tool
Common causes
Most likely first
- Damaged, corroded, or disconnected wiring or connector at the HVAC moduleLikely
- Lost power or ground feed to the moduleCommon
- CAN bus fault between the HVAC module and the networkCommon
- Failed HVAC control moduleLess often
- Blown fuse feeding the climate control systemLess often
How to diagnose & fix
Work through it in order
- Scan all modules and confirm whether the HVAC module responds at all.
- Check the fuse, power, and ground feeding the HVAC control module.
- Inspect the module's connector and wiring for corrosion or damage behind the dash.
- Check the CAN circuits between the module and the gateway for opens or shorts.
- If power and wiring are good but the module stays silent, replace it, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0164?+
Can I just clear U0164?+
Related codes
Often seen with U0164
Read & clear U0164 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.