Kenworth T680 HVAC Fault SPN 520212 FMI 14 Configuration Mismatch

Question

I am getting a persistent HVAC configuration error on my 2021 T680 and the sleeper blower motor is completely unresponsive. The dash unit works fine but the sleeper controls are dead and the CECU is throwing a mismatch code. Everything was working fine until we had a jump start situation last week.

Mike Reynolds · Accepted Answer

The issue was definitely caused by the jump start spiking the Sleeper HVAC Control Module. I had to replace the sleeper control panel unit (Part # Q21-6138-111) and then use DAVIE4 to perform a 'Chassis Node Refresh' to re-sync the HVAC configuration with the CECU. Once the parameters were re-downloaded to the new module, the fault cleared and the blower motor started working immediately. Cost was about $340 for the panel and an hour of shop time for the programming.

Kevin Tran · Answer

This code usually means the CECU doesn't see the sleeper HVAC control head or thinks it is a different model. Since you had a jump start and voltage spike, check the CAN bus wiring behind the sleeper panel for any damage.

garagegrease · Answer

Verify the resistance on the HVAC CAN line. If you are seeing 120 ohms instead of 60, you have a terminated load issue or a disconnected module pin.

Luis Hernandez · Answer

You need to use PACCAR DAVIE4 software to check the parameter settings. Sometimes the sleeper HVAC config gets flipped to 'Not Installed' in the software after a low voltage event.

Kenworth T680 HVAC Fault SPN 520212 FMI 14 Configuration Mismatch

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