FAW Air Duct: The 5 Critical Components for Flawless, Total Cab Climate Control

Welcome to this in-depth analysis of the FAW Air Duct (Assembly 713) system. This is the complete, 5-component-type, “air distribution network” for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This is the “respiratory system” of the cab, a “logic” assembly designed to take the conditioned air (hot or cold) from the ‘Dual-zone box’ (Assembly 710) and deliver it to the correct locations.

The “logic” of the FAW Air Duct system is “high-efficiency airflow.” It is a network of pre-molded, sealed plenums and channels that ensure the *maximum* volume of air from the ‘FAW Fan’ (Assembly 711) reaches its destination (windscreen, face, or feet) with *minimum* “pressure loss” or “leakage.” This “logic” is critical for fast defrosting and efficient A/C performance.

This expert guide is essential for HVAC technicians and parts managers. We will deconstruct the entire FAW Air Duct assembly into its 5 distinct serviceable component types. We will analyze the “Safety Logic” (defrost) of the side ducts, the “Comfort Logic” (face/central) of the main ducts, and the “Polymer-Safe” anti-rattle fastener system (Component 1) that holds it all together.

Core 1: The “Safety Defrost” Logic (Components 3 & 5) (The “Longer” Module)

The most critical components of the FAW Air Duct system are those dedicated to safety. This is a “dual-defrost” system, comprised of the ‘Left side door defrost… duct assy’ (8102065-B27-C00) and the ‘Right side door defrost… duct assy’ (8102070-B27-C00).

1. The “Windscreen” Defrost Logic:

The primary “logic” of these ducts is to get hot, dry air from the ‘Heater Core’ (Assembly 709) to the ‘Front Windscreen’ (Assembly 630) as *fast* as possible. These ducts are the “plumbing” that connect the ‘Dual-zone box’ (710) to the long, thin vents at the base of the dashboard.

Their “logic” is to create a high-velocity, wide “sheet” of air that blows up the *inside* of the windscreen. This “heat transfer” logic is what melts ice and evaporates fog, making them the #1 active safety component in the HVAC system.

2. The “Side Window” Defrost Logic:

This is the “secondary” and often-overlooked “logic” of these same components. The ‘Left/Right side door defrost’ ducts (Components 3 & 5) are “dual-outlet” ducts.

A “branch” or “port” on each duct “logic” is designed to aim a *separate* stream of hot, dry air directly at the ‘Side Window’ (Assembly 634). This “side-defrost” logic is *critical* for a tractor. Its function is to keep the side window clear of fog and ice, specifically in the area *where the driver looks at the ‘Left/Right Hand Wing Mirror’ (Assemblies 702 & 703)*.

Without this “mirror-clearing” logic, the driver would be “blind” in a snowstorm, unable to see their blind spots for a safe lane change. This makes these components a key part of the vehicle’s “active safety” system.

3. The “Molded-Fit” Logic:

These FAW Air Duct components are not simple, round tubes. They are complex, 3D, “blow-molded” shapes. Their “logic” is to be *invisible*. They are designed to “snake” through the extremely tight, confined spaces *inside* the ‘Dashboard Components’ (Assembly 647) and around the ‘Welded Cab Assembly’ (617) A-pillars.

They are made from a high-temperature, rigid polymer that is “acoustically dead” to prevent “whistling” noises. A failure of one of these ducts (cracked from a bad repair, or a “pinched” seal) will cause a “leak” *inside* the dashboard, resulting in weak defrost performance and a “foggy” window, even when the ‘FAW Fan’ (711) is on high.

Core 2: The “Driver Comfort” Logic (Components 2 & 4)

This group of components is the “comfort” logic of the FAW Air Duct system.

Component 2: ‘Face air duct assy’ (8102010-B27-C00)

Component 4: ‘Central air duct transition assy’ (8102050-B27-C00)

The “logic” of this pair is to deliver high-volume, conditioned air to the *driver’s face and torso*. The ‘Central air duct’ (Component 4) is the “trunk” of the system, a large “plenum” that takes the main “face” output from the ‘Dual-zone box’ (710).

The ‘Face air duct’ (Component 2) is the “branch” that connects this central plenum to the dashboard’s directional vents. The “logic” of these ducts is “high-flow, low-noise.” Their inner surfaces are engineered to be smooth, with “radiused” (curved) bends instead of sharp corners. This “laminar flow” logic allows the ‘FAW Fan’ (711) to deliver a high-velocity stream of cold air to the driver *without* an annoying “hissing” or “whistling” sound.

Core 3: The “Polymer-Safe” Fastener Logic (Component 1)

The final component of the FAW Air Duct assembly is the 15-piece fastener kit, ‘Cross recessed pan head self-tapping screw and plain washer assy’ (002214216F6).

“Polymer-Safe” Logic: This is the “installation logic” for the entire system. All the ducts (Components 2, 3, 4, 5) are “soft” polymer. They must be fastened to “hard” mounting points on the ‘Dashboard Components’ (647) and the ‘Dual-zone box’ (710).

This fastener system is a “dual-logic” component:

• “Self-Tapping” Logic: The “screw” part is “self-tapping” (自攻螺钉). It is designed to cut its own threads into the plastic “flanges” of the ducts, creating a tight, vibration-resistant connection without a “nut.”
• “Washer” Logic: The “plain washer assy” (平垫圈组合) is the *critical* “logic.” A screw head alone would “pinch” and *crack* the plastic duct flange. The washer “logic” is to *distribute the load* over a wide surface, allowing the screw to be tightened securely *without* damaging the part.

This 15-point “anti-vibration” and “anti-crack” logic is what ensures the FAW Air Duct system remains sealed, silent, and “rattle-free” for the life of the cab.

FAW Air Duct Parts List & Specifications

The following table provides the complete, detailed breakdown of all 5 component types identified in the FAW Air Duct assembly for the FAW CA4251P66K24T1A3E5 tractor.

Specifications

The specifications for the FAW Air Duct assembly are defined by its function as the “respiratory system” for the ‘Automatic A/C’ (Assembly 710).