Code
B1242
ALFA ROMEO
B — Body
Air recirculation door power amplifier circuit
Views:
UK: 5
EN: 13
RU: 6
AI status
Completed
Completed
100%
Causes
- Blown fuse or tripped relay feeding the recirculation amplifier
- Open, shorted or damaged wiring between the HVAC control module and amplifier/actuator
- Corroded, bent or loose connector pins at the amplifier or actuator
- Failed air recirculation power amplifier or internal electronics
- Failed recirculation actuator motor (stalled or high internal resistance)
- Water intrusion or contamination in HVAC housing or connectors
Symptoms
- Recirculation door stuck open or closed (no change when commanded)
- HVAC does not switch between fresh air and recirculation modes
- Inconsistent or intermittent operation of recirculation
- Possible unpleasant odors or reduced HVAC performance
- Related DTCs stored for HVAC actuators or sensors
What to check
- Read and record all HVAC-related DTCs and freeze frame data with a capable scan tool
- Visual inspection of wiring harnesses, connectors and fuses for damage or corrosion
- Check relevant fuses and relays for continuity and correct operation
- Check connector pin condition at the recirculation amplifier/actuator and control module
- Attempt to command recirculation door using a scan tool and observe actuator movement
- Measure supply voltage and ground continuity at the amplifier connector with ignition ON
Signal parameters
- Supply voltage at amplifier: approx. 11–14 V with ignition ON (model dependent)
- Ground continuity: near 0 Ω between amplifier ground and battery negative
- Actuator motor resistance: typically low ohms; large deviations may indicate fault (refer to vehicle-specific specs)
- Control signal often a pulse/PWM from HVAC module — frequency varies by model; verify with manufacturer data
- Stall current may be significantly higher than running current; check using manufacturer test procedure
Diagnostic algorithm
- Use a diagnostic scanner to read all HVAC codes and attempt to actuate the recirculation door while monitoring live data/commands.
- Visual inspection: check for water ingress, connector corrosion, broken wires or pin damage at the amplifier and actuator.
- Check fuses/relays: verify the fused supply to the amplifier and replace any faulty components.
- With ignition ON, measure battery voltage at the amplifier supply pin; expected ~12 V. Check for voltage drop while commanding the actuator.
- Verify ground: measure continuity from amplifier ground to battery negative; repair poor grounds.
- Command the recirculation actuator and observe voltage on the control/output pins. Look for PWM or drive voltage; compare to reference values.
- Measure actuator coil/motor resistance. If open or shorted, replace actuator. If resistance is normal but no movement, check for mechanical binding.
- Perform a wiggle test on wiring/connectors while commanding the actuator to find intermittent faults.
- If wiring and actuator check good, consider replacing the power amplifier module. Verify part number and fitment.
- After any repair, clear codes and perform the recirculation function test; re-check for DTC reappearance and perform a road or system test to confirm repair.
- Note: Follow vehicle manufacturer-specific procedures and safety precautions. Do not replace control modules without confirming wiring and power/ground integrity.
Likely causes
- Loss of supply voltage or ground at the amplifier
- Short to battery or short to ground on the amplifier output
- Poor connector contact (corrosion or broken terminal)
- Amplifier internal failure after moisture exposure
- Actuator mechanically stuck causing amplifier overload and fault
Fault status
Status
The HVAC control unit has detected an electrical fault in the air recirculation door power amplifier circuit. This indicates an open/short/overload or internal amplifier failure affecting recirculation door control.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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