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AutoCodes – Generic – B3779

B3779 Code - Air Flow Control 9

Quick Answer

The Heating, Ventilation, and Air Conditioning (HVAC) control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Common causes include Faulty Mode Actuator, Mode Actuator harness is open or shorted, Mode Actuator circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
B3779 indicates Air Flow Control 9.
Common causes
Common causes include Faulty Mode Actuator, Mode Actuator harness is open or shorted, Mode Actuator circuit poor electrical connection.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code Popularity 14,758
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 16, 2020
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Code B3779 Description

The Heating, Ventilation, and Air Conditioning (HVAC) control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of an electric motor and a potentiometer. The module supplies a low reference and 5-volt reference source voltage to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes. The control circuit uses either a 0, 2.5 or 5-volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5-volt control signal commands the actuator movement in opposite directions.
OBDII Code B3779 - Air Flow Control 9 - AutoCodes.com
B3779 Code - Air Flow Control 9
What does this mean?

What are the Possible Causes of the DTC B3779?

  • Faulty Mode Actuator
  • Mode Actuator harness is open or shorted
  • Mode Actuator circuit poor electrical connection
  • Faulty Heating and Cooling Systems (HVAC) Control Module

How to Fix the DTC B3779?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

B3779 02 Air Flow Control 9 Feedback Circuit Short to Ground
B3779 05 Air Flow Control 9 Feedback Circuit Short to Battery or Open
B3779 61 Air Flow Control 9 Circuit Actuator Stuck

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3779 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B3779 code?

Need more information on how to fix the B3779 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3779 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B3779 Code

What does the OBDII code B3779 mean?

The B3779 code refers to a malfunction in the Air Flow Control 9 circuit, typically associated with the vehicle's HVAC system.

What are common symptoms of code B3779?

Symptoms include reduced HVAC performance, inability to change airflow modes, or unusual noises from the HVAC system.

What causes the B3779 code?

Common causes include a faulty actuator, wiring issues, or a malfunctioning HVAC control module.

Can the B3779 code affect engine performance?

No, this code is specific to the HVAC system and does not impact engine performance.

How do you diagnose the B3779 code?

Diagnosis involves checking the actuator’s operation, inspecting wiring and connectors, and testing the HVAC control module.

How can I fix the B3779 code?

Repairs may include replacing the air flow actuator, repairing damaged wiring, or reprogramming the HVAC control module.

Is the B3779 code safe to ignore?

While it doesn't impact drivability, ignoring it can lead to discomfort and reduced functionality of the HVAC system.

Can a weak battery cause the B3779 code?

A weak battery may indirectly contribute to HVAC system malfunctions but is not a primary cause of this code.

How much does it cost to fix the B3779 code?

Repairs typically cost $150–$500, depending on whether the actuator or control module needs replacement.

Does clearing the B3779 code fix the problem?

Clearing the code may temporarily remove it, but the underlying issue must be resolved to prevent it from returning.

Discuss the causes and fixes for B3779 OBDII Code

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