Left Blend Door Travel Too Small (ATC)

What B10A6 means

On a dual-zone (ATC) 300C, Charger or Magnum, each cabin side's blend-air door is driven by a 12-volt actuator, and the A/C-Heater control learns each door's travel by sweeping it stop-to-stop and counting pulses. B10A6 sets when the LEFT door's measured span is SMALLER than expected — the door is being stopped short of its full travel. That side of the cabin then has a reduced temperature range and often can't get fully warm or fully cold. 'Left' is the physical left of the vehicle (the driver's side on a left-hand-drive car).

Symptoms

• The left side of the cabin can't reach full heat or full cold — limited range
• That side is biased warm or cool and won't move to the extremes
• The right side of the dual-zone system still covers its full range
• B10A6 stored in the A/C-Heater module

Common causes

• A foreign object, debris, or dislodged foam seal jamming the left blend door
• Bent, broken, or binding door linkage limiting the door's travel
• A weak or seizing left blend-door actuator stalling before the stop
• Faulty A/C-Heater control (module)

Severity & driving advice

Severity: Low — Comfort fault only — safe to drive; requires a scan tool that reaches the A/C-Heater module.

Can I drive? Safe to drive; climate-comfort fault only.

Diagnostic approach

1. Read the HVAC codes and clear circuit faults first — Repair any active Control Circuit / Performance or Control Circuit Open codes for the left door before diagnosing B10A6.
2. Check the left door for obstruction and binding — Rotate the door by hand stop-to-stop; it should sweep roughly 190 degrees freely. Look for debris, a jammed seal, or bent linkage stopping it short.
3. Free the door and re-calibrate — Remove any obstruction and repair binding linkage, then run the Actuator Calibration Test.
4. If it still fails, replace the actuator — A weak or seizing actuator can stall short of the stop. Replace the left blend-door actuator and calibrate; if the code persists, suspect the control module.

Estimated repair costs

Typical US repair costs (parts & labour) for the faults behind B10A6. 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.

Make & model notes

Chrysler / Dodge / Jeep: B10A6 is the dual-zone (ATC) LEFT blend-door 'travel too small' code on LX-platform cars (300 / 300C, Charger, Magnum) and related FCA models — the mirror of B10AD and the under-travel counterpart to B10A7. Check for something jamming the left door before replacing the actuator. Calibrate with a scan tool after any actuator or control-head change.

FAQ