What this code means
B1236 may indicate an open circuit problem in the passenger side air mix control motor circuit for the HVAC system.
What the vehicle may do
- The passenger side temperature may not change correctly.
- The HVAC system may set the code during a self-diagnostic check.
- Air temperature control may be inconsistent on the passenger side.
Possible fault areas
- Possible wiring or connector issue in the passenger air mix control motor circuit.
- Possible passenger air mix control motor concern.
- Possible climate control unit concern.
Diagnostic path
Opening context
On this 2010 to 2016 Honda CR-V, B1236 points to an open in the passenger side air mix control motor circuit. In plain terms, the climate control unit may be losing the position signal or circuit connection it expects from the passenger air mix door motor. The customer may notice the passenger side temperature does not respond correctly, or the HVAC may set the code during its self-check. The broad possible fault areas are the passenger air mix control motor circuit, the wiring and connector between that motor and the climate control unit, the motor itself, or the climate control unit. Start by proving the code is active before getting into circuit checks.
Confirm the fault is present
First, clear the code with the HDS. Turn the vehicle to OFF, then back to ON. Run the HVAC self-diagnostic with either the HDS or the climate control unit, then check for codes. If B1236, or the matching display code 43, comes right back, continue to the circuit checks. If it does not return, treat it as an intermittent. At that point, concentrate on loose wires or poor connections in the passenger air mix control motor circuit instead of forcing a hard-fault diagnosis that is not present right now.
Check the passenger air mix motor signal feed
With the code confirmed, turn the vehicle OFF and disconnect the passenger air mix control motor 7P connector. Turn the vehicle back ON. Measure voltage from terminal No. 2 at that disconnected 7P connector to body ground. You are looking for about 5 V. If about 5 V is present, that side of the circuit is considered OK and the next check is the shared sensor return side. If about 5 V is not present, move to the same circuit at the climate control unit connector to see where the open is showing up.
Check the sensor return side at the motor connector
Leave the vehicle in ON mode and leave the passenger air mix control motor 7P connector disconnected. Now measure between terminal No. 2 and terminal No. 3 at that same motor connector. Again, the expected reading is about 5 V. If about 5 V is present here, the SENSOR COM side of the circuit is OK, and the diagnostic path calls for replacing the passenger air mix control motor. If about 5 V is not present, repair the open in the wire between the climate control unit and the passenger air mix control motor.
Check the signal at the climate control unit
If the first motor-connector check did not show about 5 V, keep the vehicle ON and keep the passenger air mix control motor connector disconnected. Measure voltage from climate control unit 32P connector terminal No. 21 to body ground. The expected value is still about 5 V. If about 5 V is present at the climate control unit but not at the motor connector, repair the open in the wire between the climate control unit and the passenger air mix control motor. If about 5 V is not present at the climate control unit, the AMD P AS circuit is considered OK by this path, and the diagnostic result is to replace the climate control unit.
Confirmation and takeaway
Keep the confirmation separate from the pinpoint checks. Use the same self-diagnostic routine from the beginning: clear the code, cycle the vehicle OFF and ON, run the HVAC self-check, and confirm B1236 does not come back. The key on this one is not to guess at the motor or the control unit. Prove whether the about 5 V circuit is present at the motor, prove the return side, and only then follow the branch the test results give you. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis is about proving where the air mix motor circuit opens before deciding whether the fault is in the wiring, the motor, or the climate control unit.
For more guided automotive diagnostics, visit STEP Diagnostics.
