The outdoor unit of an air conditioning system is commonly referred to as the condenser or condensing unit. This unit sits outside the home and works in tandem with the indoor evaporator coil to provide cooling. Understanding the different parts and functions of the outdoor AC unit can help homeowners properly maintain their air conditioning system.
What Does the Outdoor AC Unit Do?
The outdoor AC unit, also known as the condenser, plays a vital role in the air conditioning process. Here are the key functions of this component:
Heat Rejection
As warm refrigerant from the indoor evaporator flows into the condenser, the refrigerant is cooled and condensed from a gas back into a liquid state. The heat absorbed from inside the home is rejected outdoors through the condenser.
Circulation
The condenser houses the compressor, which pressurizes the refrigerant and pushes it through the system in a continuous loop between the indoor and outdoor units. This circulation of refrigerant is what enables heat absorption and rejection.
Heat Dispersion
Fins and coils on the exterior of the condenser help disperse heat into the outside air through conduction and convection. This dispersion ensures the continuous cooling of refrigerant required for proper system operation.
Storage
The condenser provides a reservoir for excess refrigerant in the system. This storage capacity prevents refrigerant from backing up and enables smooth circulation.
What are the Main Components of the Outdoor Unit?
While the overall purpose of the outdoor AC unit is condensation and heat rejection, it contains several smaller components that enable it to perform these functions:
Compressor
The compressor is the central pump that pressurizes refrigerant gas and circulates it throughout the system. It raises the temperature and pressure of the gas coming from the evaporator to facilitate condensation.
Condenser Coils
Made of copper tubing, the condenser coils provide extensive surface area for heat transfer. As hot refrigerant passes through these coils, heat is dissipated to the external air.
Condenser Fans
Condenser fans blow air across the coils and fins of the condenser. This facilitates heat dispersion and keeps the unit from overheating.
Capillary Tube
A long, narrow tube that reduces refrigerant pressure after exiting the condenser. This drop in pressure converts the refrigerant back to a liquid.
Condenser Fins
Thin, closely-spaced metal fins attached to the condenser coils help increase surface area for improved heat transfer to the air.
Electrical Box
Houses electrical components and connections for the condenser unit. This includes wiring for the compressor and condenser fans.
Base Pan
A metal pan that sits under the condenser unit to catch condensation drainage. This prevents water from pooling around the base.
What Are the Different Types of Outdoor AC Units?
There are a few different classifications of outdoor AC condenser units:
Split Systems
This is the most common type of outdoor AC unit. It is part of a split system with an indoor evaporative coil. The two connect through refrigerant lines.
Packaged Units
Contains both evaporator and condenser coils in one outdoor cabinet. Used where there is no existing ductwork.
Mini Splits
Compact, lightweight condensers designed for smaller spaces like additions or garages. Connect to an interior wall-mounted evaporator.
Heat Pumps
Have a reversing valve that allows them to both heat and cool. Can extract heat from outdoor air and pump it indoors.
What Should I Look for When Choosing an Outdoor AC Unit?
Here are some key factors to consider when selecting an outdoor air conditioner:
Tonnage
The unit’s cooling capacity measured in tons. Must be properly matched to the size of your home.
SEER Rating
Seasonal Energy Efficiency Ratio. Higher SEER ratings indicate greater efficiency and energy savings.
Coil Material
Copper is more durable than aluminum. Thicker gauge coils improve heat transfer.
Compressor Type
Scroll compressors run more smoothly and quietly than reciprocating types.
Sound Rating
Important if the unit is near windows or patios. Look for a low decibel rating.
Quality Certifications
Look for AHRI certification to ensure performance and safety standards are met.
Warranty
A longer warranty provides more protection for the condenser’s major components.
Where Should the Outdoor AC Unit Be Located?
Proper placement of the outdoor AC unit is important for performance and efficiency. Here are some guidelines on condenser positioning:
Airflow
Place the unit where it will have ample airflow on all sides without obstructions from bushes, fences or walls.
Shading
Some shade from the hot afternoon sun will reduce strain on the unit. But avoid too much shade which can hinder airflow.
Level Surface
The unit should sit on a solid, level concrete pad or blocks to prevent vibration and noise.
Convenience
Try to locate it in a spot that allows easy access for maintenance and repairs.
Drainage
There should be adequate drainage from the base pan away from the home’s foundation.
Distance
Locate within an acceptable distance from the indoor unit based on line set limitations.
Noise
Position it away from patios, decks, walkways, and open windows where noise will carry.
Local Codes
Be sure to follow any zoning setback requirements in your municipality.
How Does the Condenser Unit Work With the Evaporator Coil?
The outdoor condenser and indoor evaporator coil work as a team to pump heat out of a home during cooling:
Evaporator
Absorbs indoor heat into refrigerant, causing it to evaporate into a gas. This produces cooling.
Compressor
Draws in low-pressure gas from evaporator and compresses it to a hot, high-pressure gas.
Condenser
Releases heat from the hot refrigerant gas so it condenses back into a liquid.
Expansion Valve
Causes a pressure drop in liquid refrigerant, lowering its temperature before returning it to the evaporator.
By leveraging changes in refrigerant pressure and temperature, this cycle continuously absorbs and rejects heat to maintain indoor comfort.
What Maintenance Does the Outdoor AC Unit Require?
To keep the condenser running efficiently, it’s important to perform regular maintenance:
Coil Cleaning
Use a hose and sprayer to wash debris and dirt from the condenser coils.
Fin Straightening
Straighten any bent condenser fins with a fin comb to improve airflow.
Filter Replacement
Replace any reusable filter screens in the condenser cabinet per the manufacturer’s instructions.
Inspections
Check wiring connections, refrigerant lines, and base pan for leaks/blockages.
Landscaping
Cut back any foliage or branches growing near the unit that hinder airflow.
Heat Pump Maintenance
For heat pumps, also clean the air intake and inspect the reversing valve.
Professional Tune-ups
Have an HVAC technician do a thorough diagnostic tune-up each year.
Troubleshooting Common Outdoor AC Unit Problems
Here are some tips for troubleshooting issues with your outdoor condenser:
Not Turning On
- Check circuit breakers or fuses
- Test voltage to unit
- Inspect wiring connections
Frozen Coil
- Low refrigerant levels
- Fan not spinning
- Debris blocking coil
- Fix refrigerant leak
High Head Pressure
- Clean condenser coil
- Check fans and airflow
- Confirm proper refrigerant charge
Noisy Operation
- Worn/loose parts
- Unit vibrating
- Issues with compressor
Refrigerant Leaks
- Listen for hissing sounds
- Check connections with soap test
- Call technician to fix and recharge
Reduced Cooling
- Dirty filters or coils
- Low refrigerant charge
- Thermostat problems
FAQ About Outdoor AC Units
What is the outdoor ac unit called?
The outdoor unit of a split air conditioning system is called the condenser or condensing unit. It sits outside the home and is connected to the indoor evaporator coil.
How does the condenser work?
The condenser rejects heat from the hot compressed refrigerant gas coming from the indoor coil. Fans blow air over the coils and fins, cooling the refrigerant back into a liquid.
What size condenser do I need?
Your condenser must be matched to the cooling demand of your home, based on square footage and other factors. An HVAC pro can determine the right tonnage.
Where is the best place to install it?
The condenser should be positioned in a spot with good airflow that won’t obstruct windows or walkways. Leave some space around the unit.
How often should I clean the condenser?
For peak efficiency, the outdoor condenser coils and fins should be rinsed off 2-3 times per year, more often if you have trees dropping debris.
Why is my condenser icing up?
Ice buildup is usually caused by low refrigerant levels, dirty filters, airflow blockages, or a failing fan motor. An HVAC pro can diagnose the issue.
What is the difference between a heat pump and AC?
A heat pump has a reversing valve that allows it to both heat and cool. A regular AC condenser does not have heating capabilities.
My condenser is making loud noises, what should I do?
Unusual noises often indicate wear, vibration or failure in components like the compressor or condenser fan motor. Have it inspected by a technician.
How long should an outdoor AC condenser last?
The average lifespan is 10-15 years. Proper sizing, regular maintenance, and quick repairs when needed can maximize the lifespan.
Key Takeaways on Outdoor AC Condenser Units
- The outdoor AC condenser, or condensing unit, sits outside and partners with the indoor evaporator coil to pump heat out of a home.
- Its main function is to cool down the hot compressed refrigerant gas from the indoor coil so it condenses back into a liquid.
- Air is blown across the coils and fins to help dissipate heat and condense the refrigerant.
- Correct condenser sizing and placement are important for proper operation. It requires regular seasonal maintenance.
- Malfunctions like frozen coils, reduced cooling, or noisy operation can indicate the need for professional troubleshooting and repairs.
- Understanding how this exterior AC component works and taking care of it will help ensure energy efficient comfort for years to come.
Sources
–Carrier – Air Conditioner Condenser Overview
–Trane – Outdoor Condensing Units
–Goodman – Condensers
–Lennox – Outdoor Ac Units
–HVAC Training 101 – Condenser Units Explained
–The Spruce – Where to Place Central Air Conditioning Condenser Units
–Fixr.com – How Much Does It Cost To Repair Central A/C?