Safe to drive; climate-comfort fault only. B10A9 means the A/C-Heater control detected a performance problem on the RIGHT blend-door actuator's control (driver) circuit — typically a short — so the control can't reliably position the right temperature door and that side of the cabin misbehaves.
What B10A9 means
On a dual-zone (ATC) 300C, Charger or Magnum, the A/C-Heater control drives each blend-air door through a two-wire door-driver circuit and monitors it. B10A9 is a 'control circuit / performance' code: it sets when that circuit on the RIGHT actuator behaves abnormally — most often shorted to voltage, shorted to ground, or the two wires shorted together — so the door can't be driven properly. The right side of the cabin then sticks or swings erratically. 'Right' is the physical right of the vehicle (the driver's side on a right-hand-drive car).
Symptoms
- The right side of the cabin is stuck or erratic and ignores the temperature dial
- Possible clicking or no movement from the right blend-door actuator
- The left side of the dual-zone system still works normally
- B10A9 stored in the A/C-Heater module
Common causes
- Right blend-door driver circuit shorted to voltage, to ground, or wire-to-wire
- Chafed or pinched harness or a corroded connector at the actuator
- Internally shorted right blend-door actuator
- Faulty A/C-Heater control (module)
Severity & driving advice
Severity: Low — Comfort fault only — safe to drive; a scan tool and the wiring diagram are needed to diagnose.
Can I drive? Safe to drive; climate-comfort fault only.
Diagnostic approach
- Read the HVAC codes — Confirm B10A9 and repair any right-door Control Circuit Open code first.
- Inspect the actuator circuit for shorts — Check the two right door-driver wires and the connector for chafing, pinching, or corrosion, and for a short to voltage, ground, or each other. Repair before testing the actuator.
- Substitute the actuator — If the wiring is clean, replace the right blend-door actuator (an internal short can trigger this code) and run the calibration.
- Replace the control if the code returns — If a good circuit and a new actuator still set B10A9, suspect the A/C-Heater control module.
Estimated repair costs
Typical US repair costs (parts & labour) for the faults behind B10A9. These are national-average estimates, not a quote— your actual price varies by region, shop labour rate, and your vehicle’s make, model and year. Figures reviewed 2026.
| Repair | Estimated cost (USD) |
|---|---|
| Wiring / connector repair | $80–$260 |
| Blend-door actuator (part) | $15–$90 |
| Actuator replacement + calibration (shop) | $90–$250 |
| A/C-Heater control module | $200–$600 |
Make & model notes
Chrysler / Dodge / Jeep: B10A9 is the dual-zone (ATC) RIGHT blend-door 'control circuit / performance' code on LX-platform cars (300 / 300C, Charger, Magnum) and related FCA models. It usually indicates a short on the actuator driver circuit — inspect the harness and connector before replacing the actuator, and refer to Section 8W for the wiring. Calibrate after any actuator or control-head change.
FAQ
What is the difference between B10A9 and B10AC?
B10A9 is a circuit 'performance' fault — usually a short on the right actuator's driver circuit. B10AC is a circuit 'open' — a break in the same circuit. Both are electrical, diagnosed at the wiring and connector, but one is a short and the other an open.
Could a chafed wire cause B10A9?
Yes — a chafed or pinched harness that shorts a driver wire to ground or voltage is a common cause. Inspect the harness routing and the actuator connector first.
Is B10A9 safe to drive with?
Yes — it only affects climate comfort on the right side of the cabin.