Understanding Ac Casing: Technical Specifications, Grades, and Application Techniques

Types of AC Casings: Structure, Function & Materials

An AC casing is a vital structural and protective component of any air conditioning system. It shields internal mechanisms from environmental damage, enhances energy efficiency, reduces operational noise, and ensures long-term reliability. Modern AC units incorporate multiple specialized casings, each designed for a specific function and operating condition. Understanding the different types helps in maintenance, selection, and performance optimization.

Outer Casing

Also known as the shell or housing, the outer casing is the first line of defense for the AC unit.

Key Features

• Made from durable metals like stainless steel or powder-coated steel
• Resistant to corrosion, UV rays, rain, snow, and extreme temperatures
• May include insulation layers to improve thermal efficiency
• Designed for structural rigidity and impact resistance

Considerations

• Heavyweight materials increase unit weight
• Poor ventilation design can trap heat
• Requires regular cleaning to prevent debris buildup

Best for: Outdoor condenser units, rooftop installations, harsh climates

Inner Casing

Located beneath the outer shell, the inner casing plays a critical role in noise reduction and component protection.

Key Features

• Constructed from lightweight metals like aluminum or galvanized steel
• Equipped with sound-dampening insulation panels
• Protects evaporator coils and airflow systems from dust and debris
• Improves air quality by minimizing internal contamination

Considerations

• Insulation can degrade over time if exposed to moisture
• Limited structural support; relies on outer casing
• Harder to access during servicing

Best for: Split AC systems, ducted HVAC units, indoor air handlers

Compressor Casing

This specialized enclosure houses the compressor—the heart of the refrigeration cycle.

Key Features

• Robust construction to withstand high pressure and vibration
• Material varies by compressor type: cast iron, steel, or reinforced composites
• Includes mounting brackets and vibration dampeners
• Designed for heat dissipation and easy maintenance access

Considerations

• Reciprocating compressors require heavier casings
• Poor sealing can lead to refrigerant leaks
• Must allow for thermal expansion during operation

Best for: All AC types with mechanical compressors, especially outdoor units

Refrigeration Casing

Encloses key refrigeration components such as evaporator and condenser coils.

Key Features

• Protects delicate copper or aluminum coils from physical damage
• Allows for controlled refrigerant flow and heat exchange
• Often includes protective fins and anti-corrosion coatings
• Designed for optimal thermal transfer while minimizing leaks

Considerations

• Coil fouling can occur if casing seals fail
• Limited airflow if design is too restrictive
• Repairs often require partial disassembly

Best for: Systems with exposed coil assemblies, commercial HVAC, split units

Fan Casing

Surrounds the fan assembly to optimize airflow and ensure safe operation.

Key Features

• Aerodynamically shaped to enhance air movement
• Available in open (grille-protected) or closed designs
• Prevents contact with rotating blades for safety
• Reduces turbulence and noise during operation

Considerations

• Grilles can collect dust and restrict airflow over time
• Poor design leads to inefficient cooling or excessive noise
• Must balance protection with ventilation efficiency

Best for: Condenser and blower fan units, both indoor and outdoor applications

Casing Type	Primary Material	Main Function	Durability	Common Applications
Outer Casing	Stainless steel, coated steel	Weather protection & structural integrity	Excellent	Outdoor units, rooftop HVAC
Inner Casing	Aluminum, galvanized steel	Noise reduction & dust protection	Good	Split systems, air handlers
Compressor Casing	Steel, cast iron, composites	Vibration damping & component safety	Very Good	All compressor-based ACs
Refrigeration Casing	Coated metal, composite	Coil protection & thermal efficiency	Good	Evaporator/condenser units
Fan Casing	Plastic, steel, aluminum	Airflow optimization & safety	Good to Very Good	Blower & condenser fans

Expert Tip: Regular inspection of AC casings—especially seals, grilles, and insulation layers—can prevent premature wear, improve efficiency, and extend the lifespan of your cooling system. Clean debris from fan grilles and check for rust on outer casings at least twice a year.

Understanding the distinct roles of each AC casing type enables better maintenance decisions, informed upgrades, and improved system performance. Whether you're a homeowner, technician, or HVAC professional, recognizing how these components work together ensures optimal cooling efficiency and durability.

AC Casing Design: Function, Materials, and Innovation

The design of an air conditioner (AC) casing plays a critical role in the unit’s overall performance, energy efficiency, noise control, and long-term durability. While the primary function of an AC is to regulate indoor temperature, the casing serves as a protective and functional enclosure for vital components such as the compressor, condenser, evaporator, and fan assembly. A well-engineered casing not only safeguards internal mechanisms but also enhances airflow dynamics, thermal insulation, and aesthetic integration into residential or commercial environments.

Modern AC casing design balances form and function, taking into account environmental conditions, user comfort, and technological advancements. For instance, fan casings are engineered to minimize turbulence and aerodynamic noise, ensuring quiet operation. Compressor casings, on the other hand, must be robust and tightly sealed to withstand high pressure, vibration, and thermal stress during operation.

Energy efficiency is a central consideration in casing design. A tightly sealed, well-insulated casing reduces air leakage and thermal transfer, allowing the system to maintain desired temperatures with minimal energy input. Additionally, advancements in smart technology have led to the integration of sensors, IoT connectivity, and predictive maintenance systems directly into the casing framework, enabling real-time performance monitoring and remote diagnostics.

Key Design Considerations for AC Casings

Aerodynamic Efficiency

Optimized airflow is essential for cooling performance and noise reduction. Casings are designed with smooth internal contours and strategically placed vents to guide air smoothly through the system, minimizing turbulence and pressure drops. Computational fluid dynamics (CFD) simulations are often used in the design phase to refine these airflow patterns.

Thermal Insulation

Effective insulation within the casing reduces heat exchange between the internal components and the external environment. This improves cooling efficiency, especially in outdoor units exposed to direct sunlight or extreme temperatures. Insulating materials such as polyurethane foam or elastomeric coatings are commonly applied to critical areas.

Noise Reduction

Sound-dampening materials and vibration-absorbing mounts are integrated into the casing to reduce operational noise. Enclosures may include acoustic liners or double-wall structures that trap sound waves, making the unit quieter—especially important for residential applications.

Environmental Resistance

Outdoor AC units face exposure to rain, UV radiation, dust, and corrosive elements. Casings must be resistant to weathering, UV degradation, and rust. Design features such as sloped surfaces, drainage channels, and sealed joints help prevent water ingress and prolong service life.

Materials Used in AC Casing Manufacturing

Historically, metal-based materials dominated AC casing production due to their strength and heat resistance. However, advances in material science have introduced lightweight, corrosion-resistant, and cost-effective alternatives. The choice of material depends on the unit type (window, split, portable, or central), operating environment, and performance requirements.

Plastic (ABS, Polycarbonate, or PVC)

Commonly used in window AC units and portable air conditioners, plastic casings offer several advantages: they are lightweight, easy to mold into complex shapes, and resistant to corrosion—making them ideal for humid or coastal climates. Additionally, plastic is cost-effective and allows for aesthetic customization. However, it has lower thermal and mechanical stability compared to metals and may degrade under prolonged UV exposure unless treated.

Aluminum

Widely used in outdoor condenser units, aluminum provides an excellent balance of light weight, corrosion resistance, and thermal conductivity. It does not rust, making it suitable for high-moisture environments. Its malleability allows for precision forming of fins and ducts, enhancing heat dissipation. While more expensive than steel, aluminum’s longevity and low maintenance make it a preferred choice for premium models.

Steel (Mild or Galvanized)

Steel remains the most widely used material for AC outer shells due to its durability, structural strength, and affordability. Galvanized steel, coated with a layer of zinc, offers enhanced protection against rust and corrosion. It is commonly used in rooftop units and industrial HVAC systems where mechanical robustness is critical. The main drawbacks are its heavier weight and susceptibility to corrosion if the coating is damaged.

Copper

Though not typically used for the entire casing, copper is occasionally employed in high-end or specialized ducted systems for components requiring superior thermal conductivity and corrosion resistance. Copper casings or linings can improve heat transfer efficiency and are highly durable. However, due to its high cost and softness, copper is generally reserved for internal components rather than full enclosures.

Material	Key Benefits	Limits & Considerations	Common Applications
Plastic	Lightweight, corrosion-resistant, low-cost, moldable	Lower heat resistance, UV degradation, less durable	Window ACs, portable units, indoor panels
Aluminum	Corrosion-resistant, lightweight, good thermal conductivity	Higher cost than plastic, moderate strength	Outdoor condensers, split units, ductwork
Galvanized Steel	Strong, durable, cost-effective, widely available	Heavy, prone to rust if coating is damaged	Industrial HVAC, rooftop units, commercial systems
Copper	Excellent conductivity, highly corrosion-resistant, long-lasting	Very expensive, soft, not structurally ideal for casings	Specialized ducted systems, internal linings

Emerging Trends in AC Casing Design

Smart Integration: Modern casings incorporate embedded sensors for temperature, humidity, and vibration monitoring. These feed data to IoT platforms for predictive maintenance and energy optimization.

Eco-Friendly Materials: Manufacturers are exploring recyclable plastics and bio-based composites to reduce environmental impact and support sustainability goals.

Sleek Aesthetics: With growing demand for home integration, casings are designed with minimalist profiles, neutral colors, and even customizable finishes to blend seamlessly into interior spaces.

Modular Design: Some systems use modular casings that allow for easier assembly, servicing, and upgrades, reducing downtime and maintenance costs.

Important: The selection of casing material and design should align with the operational environment and usage intensity. Using substandard materials in harsh conditions can lead to premature failure, reduced efficiency, and safety hazards. Always consult manufacturer specifications and consider professional advice when selecting or replacing AC units.

How To Choose AC Casing

Selecting the right air conditioning (AC) casing is a critical decision for business owners, HVAC professionals, and contractors. The casing not only protects internal components but also influences system efficiency, longevity, and ease of maintenance. A well-chosen casing ensures optimal performance across various environments and operational demands. Below is a comprehensive guide to help you make informed procurement decisions.

Compatibility with AC Components

The AC casing must be precisely engineered to accommodate all internal components, ensuring seamless integration and optimal function. Different components have varying protection and spatial requirements.

• Compressors: Require robust, vibration-dampening casings to protect against mechanical stress and noise transmission.
• Fans and blowers: Can operate in semi-open or louvered casings, provided airflow dynamics are preserved and debris is minimized.
• Ducted systems: Need casings with integrated flanges or modular joints that align perfectly with ductwork to prevent air leakage and maintain energy efficiency.
• Electrical components: Should be housed in insulated, moisture-resistant sections to reduce the risk of short circuits or corrosion.

Key consideration: Always verify dimensional specifications and mounting configurations before purchase to avoid retrofitting issues.

Corrosion Resistance

Environmental exposure significantly impacts casing durability. Corrosion can compromise structural integrity and lead to costly repairs or premature replacements.

• Coastal or high-humidity areas: Recommend casings made from stainless steel or coated aluminum with anti-corrosive finishes such as powder coating or galvanization.
• Industrial zones: Consider casings resistant to chemical exposure and airborne contaminants.
• Urban and suburban settings: Even in dry climates, seasonal humidity and temperature fluctuations can cause condensation, leading to rust over time—protective coatings are still essential.
• Inspection tip: Look for casings with UV-resistant coatings if installed in direct sunlight to prevent material degradation.

Pro tip: For maximum lifespan in harsh environments, opt for marine-grade stainless steel (e.g., 316L) which offers superior resistance to saltwater corrosion.

Budget and Cost Efficiency

While initial cost is a major factor, long-term value should guide purchasing decisions. Material choice directly affects both upfront investment and lifecycle expenses.

• Stainless steel: Higher initial cost but offers exceptional durability, minimal maintenance, and long service life—ideal for commercial or industrial applications.
• Galvanized steel: Offers a balance between strength and affordability; zinc coating provides moderate corrosion protection but may degrade over time in humid conditions.
• Aluminum: Lightweight and naturally corrosion-resistant, making it suitable for rooftop units and mobile installations. Slightly more expensive than galvanized steel but less than stainless.
• Plastic/composite materials: Most budget-friendly option, often used in residential units. However, they may lack structural rigidity and UV stability, limiting use in heavy-duty applications.

Smart investment: Calculate total cost of ownership (TCO), factoring in replacement frequency, maintenance, and downtime, rather than focusing solely on purchase price.

Operational Efficiency

An efficient casing enhances the overall performance of the AC unit by minimizing energy losses and supporting thermal management.

• Thermal insulation: Casings with built-in insulation or thermal breaks reduce heat transfer between the interior and exterior, improving cooling efficiency.
• Airflow optimization: Smooth internal surfaces and aerodynamic design reduce turbulence and pressure drops, allowing fans to operate more efficiently.
• Sealing integrity: Gaskets and weatherstripping prevent air leaks, maintaining system pressure and reducing compressor workload.
• Noise reduction: Acoustic dampening materials within the casing help lower operational noise, especially important in residential or office environments.

Critical factor: Poorly designed casings can increase energy consumption by up to 15% due to airflow restrictions and thermal bridging.

Ease of Installation

Installation complexity affects labor costs and project timelines. A user-friendly design can significantly streamline deployment, especially in constrained spaces.

• Modular panels: Casings with quick-release fasteners or snap-fit joints allow easy access for servicing without full disassembly.
• Lightweight materials: Aluminum and composite casings are easier to handle during rooftop or wall-mounted installations.
• Standardized mounting points: Ensure compatibility with common brackets and existing infrastructure to reduce customization needs.
• Pre-drilled holes and alignment guides: Facilitate faster and more accurate installation, reducing errors and rework.

Time-saving tip: Choose casings with tool-less access panels for routine inspections and filter changes.

Maintenance Requirements

Long-term reliability depends on how easily the casing can be inspected, cleaned, and repaired. Low-maintenance designs reduce downtime and service costs.

• Stainless steel & aluminum: Typically require only periodic cleaning; resistant to rust and degradation under normal conditions.
• Galvanized steel: Needs regular inspection for coating wear, especially in humid or salty environments. Touch-up painting may be required to prevent rust progression.
• Plastic casings: Prone to cracking under UV exposure or physical impact; replacement may be necessary rather than repair.
• Drainage design: Casings should include sloped bases or drain channels to prevent water pooling, which can lead to mold or corrosion.

Best practice: Provide customers with a maintenance checklist based on casing material and environment to extend system life.

Professional Recommendation: For most commercial applications, we recommend mid-to-high-tier aluminum or stainless steel casings. These materials offer the best balance of durability, corrosion resistance, and energy efficiency. In residential or budget-sensitive projects, galvanized steel with a protective finish is a practical alternative—just ensure it’s paired with proper sealing and routine inspections. Always prioritize compatibility and thermal performance over aesthetics alone.

Material Type	Initial Cost	Corrosion Resistance	Maintenance Level	Best Use Case
Stainless Steel	High	Excellent	Low	Coastal areas, industrial sites, critical infrastructure
Aluminum	Moderate to High	Very Good	Low	Rooftop units, mobile systems, commercial buildings
Galvanized Steel	Moderate	Fair to Good	Moderate	Urban/suburban installations, budget-conscious projects
Plastic/Composite	Low	Fair	Moderate to High	Residential units, temporary setups, dry climates

Additional Considerations

• Warranty Coverage: Premium manufacturers often offer 5–10 year warranties on corrosion resistance, reflecting confidence in material quality.
• Environmental Compliance: Ensure casings meet local regulations for recyclability and emissions (e.g., RoHS, REACH).
• Aesthetic Finish: For visible installations, consider powder-coated or painted finishes that match building exteriors.
• Security Features: Lockable panels or tamper-resistant fasteners are valuable for outdoor or public installations.
• Future-Proofing: Select modular casings that allow for upgrades or integration with smart HVAC controls.

Maintenance and Repair of AC Casing: A Comprehensive Guide

The durability and efficiency of air conditioning systems heavily depend on the condition of their casings. Whether your unit is part of a ductless mini-split system or a traditional ducted HVAC setup, the outer casing serves as the first line of defense against environmental damage, debris, and mechanical stress. Regular maintenance not only extends the lifespan of the casing but also enhances overall system performance, reduces energy consumption, and lowers long-term repair costs.

Safety Note: Always disconnect power to the AC unit before performing any maintenance or inspection. Avoid using high-pressure water or abrasive cleaners that could damage protective coatings or force moisture into internal components.

1. Cleaning the AC Casing

Over time, the exterior of an air conditioner accumulates dust, grime, pollen, bird droppings, and other airborne debris—especially in outdoor condenser units. This buildup not only affects the unit’s appearance but can also trap moisture, accelerating corrosion and reducing heat dissipation efficiency.

• Professional Cleaning: For optimal results and system longevity, it's recommended to hire certified HVAC technicians to perform a deep clean at least once every three months. Professionals use specialized, non-corrosive cleaning agents and soft brushes to safely remove stubborn deposits without damaging the finish.
• DIY Exterior Wiping: Between professional cleanings, homeowners can maintain the casing by wiping down the exterior weekly with a damp microfiber cloth. Use mild soap and water for light cleaning, and avoid harsh chemical solvents that may degrade paint or protective coatings.
• Focus Areas: Pay special attention to ventilation grilles, seams, and joints where dirt tends to accumulate. Ensure all cleaning residue is rinsed off to prevent chemical reactions with the casing material.

Pro Tip: After cleaning, apply a UV-protective coating or automotive-grade wax (for painted surfaces) to help resist fading and environmental damage, especially in sunny or coastal climates.

2. Routine Inspections

Conducting monthly visual inspections is a simple yet effective way to catch early signs of casing deterioration before they escalate into costly repairs.

• Check for visible cracks, dents, warping, or punctures in the casing, particularly after storms or accidental impacts.
• Look for rust spots or flaking paint, especially around fasteners, seams, and drainage areas.
• Inspect mounting brackets and screws for looseness or corrosion.
• Listen for unusual noises such as grinding, rattling, or vibrating during operation—these may indicate internal component issues or loose casing panels.
• Ensure the unit remains level and securely mounted, as misalignment can stress the casing over time.

If damage is detected early, timely intervention can prevent moisture intrusion, electrical hazards, or reduced cooling efficiency.

3. Performing Repairs

Not all casing issues require professional service. Minor damage can often be addressed by homeowners using basic tools and materials.

• Small Cracks or Holes: On plastic or fiberglass casings, temporary fixes like waterproof tape or epoxy sealant can prevent moisture entry until a permanent repair is possible. Duct tape can serve as a short-term solution but should be replaced with a more durable fix.
• Loose Fasteners: Tighten any loose screws, bolts, or clips using appropriate tools. Replace missing or corroded hardware with stainless steel equivalents to prevent future rust.
• Panel Realignment: If a panel is bent or misaligned, gently reposition it to ensure proper airflow and sealing.

Important: Major repairs—such as replacing corroded metal sections, fixing internal components, or rewiring—should always be handled by licensed HVAC professionals. Attempting complex repairs without proper training can void warranties, create safety hazards, or lead to further system damage.

Warning: Never attempt to remove or modify internal components unless qualified. Electrical components inside the casing can pose serious shock risks even when the unit is turned off.

4. Preventing Corrosion

Corrosion is one of the leading causes of premature casing failure, particularly in coastal regions, industrial zones, or areas with high humidity.

• Material Selection: When purchasing a new unit, opt for models with galvanized steel, stainless steel, or polymer-based casings that offer superior resistance to rust and environmental degradation.
• Protective Coatings: Ensure the casing has a rust-inhibiting primer and durable topcoat. Reapply protective sprays or anti-corrosion treatments annually, especially on vulnerable edges and joints.
• Environmental Protection: Consider installing a weather cover (designed for AC units) to shield the casing from direct rain, snow, and UV exposure—while still allowing proper airflow.
• Drainage Maintenance: Keep the area around the unit clear of debris and standing water to minimize moisture retention against the casing.

5. Knowing When to Replace the Casing

Despite regular maintenance, every AC casing has a finite lifespan. Replacement becomes necessary when repairs are no longer cost-effective or when structural integrity is compromised.

Signs that replacement may be needed:

• Extensive rust or pitting that penetrates through the metal
• Multiple cracks or warping that cannot be sealed effectively
• Repeated air leaks affecting cooling efficiency
• Increased operational noise due to loose or damaged panels
• Visible degradation of insulation or internal components due to casing failure
• Frequent need for repairs within a short timeframe

Replacing the casing—or upgrading to a newer, more efficient unit—can restore performance, improve energy efficiency, and extend the life of the internal components.

Maintenance Task	Frequency	Tools/Materials Needed	Recommended Action
Cleaning (Exterior)	Weekly (DIY), Quarterly (Professional)	Damp cloth, mild detergent, soft brush	Wipe down surfaces; avoid high-pressure washing
Visual Inspection	Monthly	Flashlight, notepad	Check for cracks, rust, dents, and loose parts
Minor Repairs	As needed	Screwdriver, sealant, replacement screws	Tighten fasteners; patch small holes
Corrosion Prevention	Annually (or biannually in harsh climates)	Anti-corrosion spray, protective wax	Apply rust inhibitor to vulnerable areas
Professional Assessment	Biannually or when issues arise	N/A	Consult HVAC technician for major concerns

Expert Tip: Keep a maintenance log to track cleaning dates, inspections, and repairs. This record helps identify recurring issues and supports warranty claims or professional servicing.

Final Recommendations

• Always follow the manufacturer’s guidelines for care and maintenance specific to your AC model.
• Invest in high-quality units with corrosion-resistant materials, especially in challenging environments.
• Schedule annual professional HVAC servicing to assess both internal components and casing integrity.
• Never ignore early warning signs like discoloration, moisture buildup, or strange noises.
• Consider upgrading to smart AC systems with diagnostic alerts that notify you of casing or performance issues.

By prioritizing the care of your air conditioner’s casing, you protect your investment, ensure consistent cooling performance, and contribute to a longer, more efficient system lifespan. Regular attention today can prevent expensive replacements tomorrow.

Frequently Asked Questions About Air Conditioner Casings

Q. Will an AC unit function with a faulty casing?

No, an air conditioning unit cannot operate safely or efficiently with a faulty or damaged casing. The casing serves as a critical structural and protective component for the entire system. It encloses and safeguards essential internal parts such as the compressor, condenser coils, fan motor, and refrigerant lines—where the cooling process occurs as warm air passes over cooled refrigerant coils.

When the casing is compromised, several issues arise:

• Component Exposure: Internal components become vulnerable to environmental damage, including moisture, dust, debris, and pests, which can lead to corrosion, electrical shorts, or mechanical failure.
• Reduced Airflow: Gaps or misalignments in the casing can disrupt proper airflow dynamics, causing uneven cooling, increased strain on the fan motor, and reduced system efficiency.
• Safety Hazards: Exposed electrical wiring or moving parts pose risks of electric shock or injury during maintenance or operation.
• Energy Inefficiency: Leaks in the casing reduce the system’s ability to maintain pressure and temperature, forcing the AC to work harder and consume more energy—leading to higher utility bills and premature wear.

Even minor damage should be addressed promptly to prevent escalating repair costs and ensure optimal performance, safety, and longevity of the AC unit.

Q. What's the average lifespan of an AC casing?

The average lifespan of an air conditioner casing typically ranges from **15 to 20 years**, aligning closely with the expected operational life of the overall AC unit. However, with regular maintenance and timely repairs, some casings can last up to **25 years or more**, especially in favorable conditions.

Several key factors influence the durability and longevity of an AC casing:

• Climate Conditions: Units in coastal areas face salt spray and high humidity, accelerating corrosion—especially in metal casings. Extreme temperatures and frequent weather fluctuations also contribute to material fatigue.
• Usage Frequency: Systems that run continuously due to high cooling demands experience more thermal expansion and contraction, which can weaken joints and seams over time.
• Maintenance Routine: Regular cleaning, inspection, and protective treatments (like anti-rust coatings) significantly extend casing life by preventing buildup of debris and early-stage corrosion.
• Installation Quality: Proper mounting and leveling reduce stress on the casing structure, minimizing the risk of cracks or warping.

Monitoring for signs of rust, dents, or warping during annual HVAC inspections can help determine whether repair or replacement is needed before internal components are affected.

Q. What are the most common materials used to make AC casings?

AC casings are primarily constructed from three materials—steel, aluminum, and plastic—each offering distinct advantages and trade-offs in terms of durability, weight, cost, and environmental resistance.

Material	Advantages	Disadvantages	Best Use Cases
Steel	High strength, excellent durability, resistant to impact and deformation, ideal for heavy-duty outdoor units.	Prone to rust if not properly coated; heavier than alternatives, making installation more difficult.	Residential and commercial units in moderate climates with protective powder coating.
Aluminum	Lightweight, naturally rust-resistant, good heat dissipation, easy to shape and install.	Less rigid than steel; can dent under strong impact; generally more expensive than plastic.	Coastal regions, high-humidity environments, and modern compact units where corrosion resistance is crucial.
Plastic (Polymer Composites)	Affordable, lightweight, immune to rust, easily molded into complex shapes for improved aerodynamics.	Lower durability; susceptible to UV degradation, cracking in cold weather, and warping under heat stress.	Indoor units, window ACs, and budget models where exposure to harsh elements is limited.

Many modern AC units use hybrid designs—such as steel frames with aluminum panels or UV-stabilized plastic enclosures—to balance strength, weight, and corrosion resistance. When selecting or repairing a casing, consider your local environment and usage patterns to choose the most suitable material for long-term reliability.