B1262

Code

Other B — Body

Servo Motor Defrost Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 25 EN: 36 RU: 27

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Page language: EN

Causes

Blown fuse or relays supplying the HVAC actuators
Open, shorted or corroded wiring/connectors in the servo motor circuit
Poor or missing ground at the actuator
Failed servo motor or internal gears (mechanical seizure)
Faulty HVAC/Body control module or software fault
Water intrusion or contamination in connector or actuator

Symptoms

No defrost or incorrect airflow distribution (vent selection stuck)
HVAC vents do not move to defrost position or are slow/intermittent
Interior may show an HVAC warning or stored B1262 code in scan tool
Heater/AC blower may operate normally while door position is incorrect
Clicking or no noise from actuator when HVAC mode changes

What to check

Scan for stored HVAC/body codes and freeze-frame data with a diagnostic scanner
Visually inspect fuse(s) and relays related to HVAC/actuator circuits
Inspect connectors and wiring to the defrost actuator for corrosion, pin damage, or water ingress
Wiggle test wiring while actuating to check for intermittent faults
Check for mechanical binding by attempting to move the duct doors by hand where accessible (power off)
Verify actuator receives proper supply voltage and ground at connector with key on and HVAC commanded to defrost

Signal parameters

Supply voltage: switched 12 V feed to actuator when commanded (verify with multimeter)
Control input: PWM or DC command from HVAC module; duty cycle varies with position command
Position feedback: voltage signal typically 0–5 V or variable voltage proportional to door position
Current draw: actuator idle and operating current usually low (typically under a few amps); significant increase indicates binding or stalled motor
Continuity/Resistance: motor windings and feedback potentiometer show measurable resistance (check manufacturer data if available)

Diagnostic algorithm

Retrieve and document all HVAC/body codes and freeze-frame data with scan tool; note any related codes
Visually inspect fuses, relays and wiring to the defrost actuator for obvious damage or corrosion; repair as needed
With connector connected, command defrost mode and measure supply voltage at actuator power pin(s); should be battery/ignition voltage when commanded
Measure ground continuity from actuator ground pin to chassis ground; ensure low resistance
Backprobe or measure the feedback/position signal while commanding different vent positions; verify feedback changes consistently (0–5 V or expected range)
If no supply or ground, trace and repair wiring, fuses, or module outputs before replacing actuator
If supply and ground are correct but actuator does not move, remove actuator and bench-test with a fused 12 V supply to confirm operation; inspect gears for stripping or seizure
If actuator works on bench test but not in vehicle, re-check wiring harness and HVAC control module outputs; consider replacing actuator or control module as guided by tests
After repair or replacement, clear codes, cycle HVAC through modes and verify operation and that B1262 does not return
If intermittent, perform wiggle tests and re-check connections under different temperatures; consider sealing connector against moisture

Likely causes

Broken or corroded connector pins at the servo
Open/short in the power feed or ground for the defrost actuator
Failed position-feedback potentiometer or sensor inside the servo
Mechanical binding or stripped gear in the actuator preventing movement
Blown fuse or intermittent supply voltage from the HVAC control module

Fault status

⚠️ Status

Control module detected a fault in the defrost servo motor circuit: no valid power/ground or invalid position feedback (open, short, or inconsistent signal).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours