2023 Freightliner Cascadia Front HVAC Controller - Diagnostic Information Updates

Applicable Vehicles

All Cascadia (P3) daycab and sleeper cab

Symptoms

N/A

Issue

There is a severe supply constraint on the main HVAC controller, A22-60645-101. An electronic component is no longer available to manufacture the main HVAC controller. Part supplies are extremely limited, and there are no alternative parts.

As information is gathered to identify reasons that the HVAC controller is being replaced, this Solution will be updated with new troubleshooting information intended to identify situations where the controller does not require replacement.

Solution

Known nuisance fault code 

Nuisance Fault Code: SA 25 - SPN 523318 - FMI 7, Blower Motor Rotor Blocked or Speed Mismatch

This fault code is intended to set when feedback from the blower motor indicates that the rotor has stalled. It is frequently triggered under the following circumstances:

1. Blower speed is set higher than position 3 on the HVAC control head.
2. Blower motor is operating with the key in the RUN position and the engine is NOT running
3. The key is turned to the START position to start the engine.

Power to the blower motor is cut off during starting, causing the rotor speed to drop. The HVAC controller remains powered during starting, and the controller incorrectly interprets the speed change as a blocked rotor.

If there is air coming out of the HVAC system vents, and the blower speed control is able to change the blower motor speed (for example, change from position 3 to position 8), then it is very likely that this code is a nuisance code.