What is The Inside AC Unit Called? (And Outside)

Most don’t overthink the life of our AC units. We switch them on to get a reprieve from the heat, expect cold air instantly, and forget about them. That is until they don’t work.

While there are five types of popular AC methods for cooling our homes, we’re looking at central air (CA) and heat pump (HP) systems.

The inside and outside units work together to provide air conditioning to our ideal interior home temperature. 

Below you’ll find in-depth explanations for both the inside and outside AC units.

Let’s dive in.

What Is the Inside AC Unit Called

An evaporator coil is the internal portion of an AC unit. This coil is housed in a metal box (plenum) located inside the air handler. 

Inside units or indoor coils are common names for the evaporator coil in the AC industry.

What the Inside Unit of Your Air Conditioner Does

The inside coil housed in an air handler of your air conditioner handles the flow and distribution of warm air away from the inside of your home. 

In simple terms, an evaporator coil absorbs heat from the hot air trapped inside your home.

This coil is located on top of your furnace or inside the air handler HP systems (usually stored in the garage, attic, basement) and works in tandem with the condenser coil to produce coveted cool air.

Note that horizontal units stored in attics often have the evaporator coil housing on one end of the furnace instead of on top.

What the Outside Unit of Your Air Conditioner Does

You know this part of the AC because it makes noise.

The noise comes from the compressor that operates the condenser coil, the many necessary electrical components, and a fan. 

Most often located at the side or back of the house, this part of the AC unit helps complete the endless cycle.

The refrigerant flows through a network of pipes from the inside and releases the hot air into the environment.

How Does It Do That?

The external compressor coil pushes the refrigerant through the network of lines to the interior evaporator coil to attach the warm air and move it outside.

Of course, there are many other parts like fans to create suction and movement, electricity, a motor, and HVAC lines to help this process along.

The refrigerant is a working fluid that constantly moves and changes from gas to liquid and back to gas.

5 Major Parts of An Air Conditioner

Four critical components responsible for moving the air are the evaporator, condenser, expansion valve, and compressor located either inside or outside the unit. 

However, one more important feature often not mentioned is the thermostat.

1. Evaporator

This coil is located on the cool side inside your home and receives the liquid refrigerant. A fan blows air over the cold coil into your home.

In central air systems, the evaporator coils are inside. With newer heat pumps, those coils require a lower atmosphere and are best operated outside.

During this process, the evaporator coil converts the liquid refrigerant into a gas where the pressure drops.

2. Condenser

Located on the hot outside, the condenser is the evaporator’s best friend.

It manages the heat transfer. Easy to identify, the condenser looks like a car radiator. 

It does the opposite of the evaporator by converting the gas released by the evaporator back into a liquid in a continual exchange. 

This exchange is called heat transfer. Heat moves from a warmer to a cooler substance.

3. The Expansion Valve

The primary function of the expansion valve is to regulate the refrigerant flow into the evaporator coil by removing the pressure from its liquid form and converting the refrigerant back into a gas inside the evaporator.

Thermal expansion valves (TEV, TX, TXV) are metering devices that assist the evaporator and condenser coil in the process of converting gas to liquid in a continuous exchange.

You can find the TX between the fluid line of the condenser and the inlet of the evaporator.

4. Compressor

The compressor is the powerhouse that stands behind the efficiency of your air conditioning unit.

It consumes energy and is the most expensive component of your system to replace.

Its main function is to compress refrigerants.

Warm vapor/gas arrives in the compressor where the coils convert the gas to a hot liquid.

This process releases the hot air captured from inside the home to the outside.

Caveat: While refrigerant (Freon) leaks are rare and accidental inhalation is mild, always use caution when dealing with this odorless and tasteless gas. Consult a medical professional if you think you’ve been exposed and exhibit symptoms.

5. Thermostat

Thermostats are the brain behind our heating and air conditioning and tell the HVAC systems at what temperatures to switch off and on.

The best place to position a thermostat is away from direct sunlight and heat vents, usually a hallway.

Modern thermostats are great partners for controlling the temperature to conserve energy, whether you’re at home or at the office.

If you’re wondering what temperature to keep your AC when away, check out our guide.

Other Air Cooling Systems

All air conditioning units operate on the same basic principles. Some are costly and permanent; others are inexpensive when you need them.

Window Units

Air conditioning systems have evolved. Although many people still use window units, the same units we’ve watched fall from windows in movies; their downside is that they’re not attractive.

Modern window units are efficient and affordable.

Ductless Mini-Split 

A great option to consider is ductless/mini-split air conditioners.

The components that make these miniature air conditioners work rely on the same principle as regular units.

They’re wall-mounted and can deliver cooling or heating to confined spaces but don’t require any ductwork.

Ductless units are perfect for cooling one living or sleeping space.

So if you can tolerate the heat during the day but want to sleep in a cooled bedroom, they’re ideal. 

Portable Units

Portable units are an excellent option for small spaces, rental units, or cabins.

Technology has caught up to these units, and they’re efficient if used correctly for their purpose and size.

They don’t require any installation.

Final Thoughts on AC Units

Technology constantly shifts innovation forward, and air conditioning services are big business.

Add global warming to the picture, and many areas that used to fight heat with ceiling fans or floor models are switching to installing air conditioning units.

Image Credits: Wikipedia

About Roy Cohen

Roy Cohen has a burning passion for heating, cooling, and ventilation. He aims to help you save money on expensive repairs and bring you the best HVAC products. He has years of experience behind him in HVAC repair and garage maintenance.

You can find Roy at his LinkedIn or his email: [email protected]

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