F31130903 | Genuine Paccar® Air Inlet Assembly

1. Controls Fresh vs. Recirculated Air

The main job is to determine where the air comes from:

• Fresh Air Mode: Pulls air in from outside the vehicle

• Recirculation Mode: Reuses the air already inside the cabin

These modes help with comfort, air quality, and cooling efficiency.

2. Provides Airflow to the HVAC System

The assembly is the entry point where air first enters the blower motor.
Without it, the HVAC system can’t receive proper airflow.

3. Works With Climate Control

The air inlet door opens and closes based on:

• Driver input

• Automatic climate control commands

• Defrost settings

4. Protects the HVAC System

Some assemblies include:

• Cabin air filter housing

• Grilles/screens to block debris, leaves, dust, and insects

1. Airflow Is Weak or Poor

• Air coming from the vents feels weak, even on high

• Happens because the inlet door may be stuck in the wrong position

2. HVAC Stuck in Fresh or Recirculation Mode

• Recirculation button does nothing

• You cannot switch between fresh air and recirculated air

• Air may smell stale because it’s stuck on recirc

• Wind noise or cold drafts if stuck on fresh air

3. Clicking or Ticking Noise Behind the Dashboard

Usually heard when:

• First starting the car

• Switching recirculation mode
  This is caused by a failing air inlet actuator or broken door gears.

4. Poor AC Performance

• AC may not cool well if stuck on fresh air

• AC may fog windows or smell musty if stuck on recirculation

5. Foggy Windows

If the inlet door is stuck in recirculation:

• Moisture builds up

• Windows fog up easily

6. Air Smells Bad or Musty

If the door doesn’t open properly, airflow gets restricted, leading to:

• Mold

• Mildew buildup
  This often happens when recirculation stays on too long.

7. No Response From the Control Buttons

• Pressing the recirculation button results in no change

• No sound or movement from behind the dash