Left Blend Door Actuator Performance (ATC)

What B10A8 means

On a dual-zone (ATC) 300C, Charger or Magnum, the A/C-Heater control drives each side's blend-air door with a 12-volt actuator and monitors the door-driver circuits during movement. B10A8 is the LEFT 'actuator performance' code: it sets when the control detects a pulse-count error while driving the left actuator — the door isn't moving as instructed. It reports that movement was interfered with but not the exact cause, so more testing is needed. The left side of the cabin behaves erratically or sticks at one temperature. '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 is erratic or stuck at one temperature
• That side works intermittently as the door binds
• Possible clicking or straining from the left blend-door actuator
• B10A8 stored in the A/C-Heater module, often with B10A7

Common causes

• Left blend-door actuator binding internally or physically broken
• Door linkage binding, disconnected, missing, or broken
• Door-driver circuit shorted high, low, wire-to-wire, or open
• Faulty A/C-Heater control (module)

Severity & driving advice

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

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

Diagnostic approach

1. Read the HVAC codes — On the A/C-Heater module, repair any Control Circuit / Performance or Control Circuit Open codes for the left door before diagnosing B10A8.
2. Run the Actuator Calibration Test — Command a calibration and watch which fault reports as the door sweeps — binding or a slipping linkage shows up here.
3. Check the actuator and linkage — Confirm the left door swings freely by hand (~190 degrees) and the linkage is intact. Repair or free any mechanical problem.
4. Replace the actuator, then the control if needed — If circuit and linkage are good, replace the left blend-door actuator and calibrate. If B10A8 persists, suspect the A/C-Heater control module.

Estimated repair costs

Typical US repair costs (parts & labour) for the faults behind B10A8. 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: B10A8 is the dual-zone (ATC) LEFT blend-door 'actuator performance' code on LX-platform cars (300 / 300C, Charger, Magnum) and related FCA models — the mirror of B10AF. It is set during normal door movement when the control sees a pulse-count error, so it commonly appears with B10A7. Check the door and linkage before condemning the actuator; calibrate after any actuator or control-head change.

FAQ