2010 Cascadia HVAC SA25 SPN523331 04??

SA 25 SPN523331 FMI 4 is Recirc Door Actuator-voltage below normal, open circuit.
It appears like Recirculation Actuator Stepper Motor is supplied with power on LT BLU 338A4+ from pin 26 of Front control Unit (FCU) to stepper motor at pin2. Then there are 4 grounds on from stepper motor to FCU. But better to post the last six of your VIN if you want more detailed & accurate information.

 

@OneTwentyOne You should thank SWM_tech's post...and also supply last 6 of your vin.

 

Here's the schematic for the recirc actuator.



You should see the plenum just to the right of the dog house. The recirc actuator is underneath the blower motor. I bet water or something got on it. At any rate, test the wiring.

 

SA 25 SPN523331 FMI 4 is Recirc Door Actuator-voltage below normal, open circuit.
Suggests that there is a wiring problem. Voltage below normal suggest there may be high resistance in wiring or an open means the wire might be completely broken.
Each on of the four ground wires and the power wire that connects to the re-circulation Actuator Stepper Motor from the Front Control Unit (FCU) needs to be checked for integrity.
I haven't faced this specific problem but generally speaking you need to unplug the harness at the stepper motor and and the front control unit. Then using a multi-meter in the continuity setting check for continuity on each of the four ground wires and the the power wire. RocketyMan has already posted the wiring diagram that has the wire color, circuit number and pin number in the connectors.
If you have continuity then set your multi-meter to resistance and check the ohms. I would think for short wiring distance would be 0.3 ohms or less. Additionally, I have sometimes used a headlight that would be about 4 amp load and connected both ends of wire in question inline as part of circuit to power my test headlight for a couple seconds.. If test headlight lights up nice & bright your wire is good.

If wire testing is more than your comfortable doing I suggest that the dealership might be a good option.

 

Here is more simple wiring schematic that might be helpful.