Safe to drive; climate-comfort fault only. B10A7 means the A/C-Heater control measured too much travel on the LEFT blend-door actuator during calibration — the left-side temperature door over-travels or the actuator turns without a firm stop, so that side of the cabin usually ends up stuck at one temperature.
What B10A7 means
On a dual-zone (ATC) 300C, Charger or Magnum, each cabin side has its own blend-air (temperature) door driven by a 12-volt actuator. During calibration the A/C-Heater control drives the door to a soft stop and counts pulses to the opposite stop to learn the door's travel span. B10A7 sets when the LEFT door's measured span exceeds the expected high limit — the door over-travels, a stop is missing or broken, or the actuator is slipping on a worn cam. That side of the cabin then blows a fixed temperature (often full hot) regardless of the dial. 'Left' is the physical left of the vehicle: the driver's side on a left-hand-drive car, the passenger side on a right-hand-drive car.
Symptoms
- The left side of the cabin stays hot (or cold) whatever temperature you set
- Only the left side is affected; the right side heats and cools normally
- No response on that side when adjusting the temperature
- B10A7 stored in the A/C-Heater module, sometimes alongside B10A8
Common causes
- Worn, broken, or missing left blend-air door, cam, linkage, or door stop allowing over-travel
- Warped or cracked A/C-Heater housing that has moved the door's physical stops
- Left blend-door actuator slipping on its splines or failing internally
- Faulty A/C-Heater control (module), confirmed only after the door and actuator are ruled out
Severity & driving advice
Severity: Low — Comfort fault only — safe to drive. A scan tool that communicates with the A/C-Heater module is required to diagnose it.
Can I drive? Safe to drive; climate-comfort fault only.
Diagnostic approach
- Read the HVAC module codes first — With a scan tool that reaches the A/C-Heater module, repair any active Control Circuit / Performance or Control Circuit Open codes before diagnosing B10A7.
- Inspect the left blend door and housing — Look for worn, disconnected, missing, or broken linkage, a warped or broken housing, and missing seals. Rotate the door stop-to-stop; it should sweep about 190 degrees. Repair any mechanical fault.
- If the door is sound, replace the left blend-door actuator — The actuator bolts onto the left end of the heater housing behind the lower-dash trim. Align its output-shaft splines with the door cam on fitting.
- Calibrate and re-check — Run the scan-tool Actuator Calibration Test. If B10A7 still sets, replace the A/C-Heater control module; if it clears, the job is done.
Estimated repair costs
Typical US repair costs (parts & labour) for the faults behind B10A7. 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) |
|---|---|
| Blend-door actuator (part) | $15–$90 |
| Actuator replacement + calibration (shop) | $90–$250 |
| Blend door / housing repair (dash out) | $400–$1,100 |
| A/C-Heater control module | $200–$600 |
Make & model notes
Chrysler / Dodge / Jeep: B10A7 is the dual-zone (ATC) LEFT blend-door 'travel too large' code on LX-platform cars (300 / 300C, Charger, Magnum) and related FCA models — the mirror of B10AE. It causes a 'one side stuck hot/cold' complaint on the left of the cabin (driver's side on a left-hand-drive car). The actuator is a three-screw, one-connector bolt-on behind the lower-dash trim; torque to 2 N·m (17 in-lb) and run the Actuator Calibration Test after replacing the actuator or control head.
FAQ
Can I drive with a B10A7 code?
Yes — it only affects climate comfort on the left side of the cabin and is not a safety fault, though that side will be stuck at one temperature until repaired.
Is B10A7 the same as B10AE?
They are mirror codes. B10A7 is the LEFT blend door 'travel too large'; B10AE is the RIGHT blend door. The cause and repair are the same, just on opposite sides of the cabin.
Can a calibration clear it?
If the door, cam and linkage are mechanically fine, re-running the Actuator Calibration Test can re-learn the stops and clear B10A7. If something is worn or broken it will come back and the actuator (or door) needs attention.