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Air conditioning

We all relish the ultimate chill blasting out of our car dashboard vents when the A/C system kicks in on those hot days. Believe it or not,  an air con system needs to be maintained and replaced quite often in your car. In fact, the cold air generated by your air conditioner is actually hot air with the gases removed during a multi-step cooling process. In this article we will look at some of the most important parts and elements that make up your car air conditioning system such as a compressor, condenser, receiver or accumulator. 

HOW DOES THE A/C SYSTEM WORK IN YOUR CAR?

Cliff’s note version of thermodynamics is simply about changes in pressure causing changes in temperature. Turn the A/C on and the compressor compresses the system’s refrigerant (Freon) raising its temperature. It loses heat as it flows through the condenser. It passes through the receiver/dryer, where contaminants and moisture are removed, and then on to the expansion valve/accumulator, where the refrigerant is slowed down further, causing it to lose pressure and temperature before it gets to the evaporator. The evaporator is like a mini radiator inside the dash of your car that gets cold as it further lowers the temperature of the refrigerant and, additionally, removes moisture from the air.

HOW OFTEN DO I NEED MY A/C SYSTEM TO BE “RECHARGED”?

You can only feel the cool breeze when it no longer feels as chilly as you remember. Simple enough. Now, it is true that a well-maintained A/C system can last its entire life without needing a recharge. But, that’s if you’re extremely lucky.

If you notice your A/C isn’t cooling your car down, have your system inspected. In this situation, most cars will be low on Freon. And since the A/C is a sealed system, low Freon is a big sign that something is not right. We’ll perform an A/C Performance Check and get to the root of the problem. We’ll get you back out there cruising with a nice, cool breeze again.

WHAT ARE THE MOST IMPORTANT PARTS THAT MAKE UP A CAR A/C SYSTEM?

Your A/C system consists of five major parts, all working together to cool you off and all your passengers.

Most A/C systems are built with:

  • Compressor
  • Condenser
  • Receiver drier or Accumulator
  • Orifice tube or Expansion valve
  • Evaporator

Your A/C system also consists of hoses and refrigerant charging ports, but the significant work occurs in the five parts listed above. You can learn more about each part that makes up your A/C system starting with the next question. Cool.

WHAT IS THE A/C COMPRESSOR?

You need a working compressor to create cold air. We’ve seen people try to create cold air without one, but trust us, it doesn’t work.

The compressor:

  • Pressurises the refrigerant that cools your air.
  • Senses temperature changes: Compressors monitor and control temperature output with an electrically operated clutch. This clutch turns on and off whenever you change the temperature, choose a different airflow setting or just when plain old air from outside drops or rises in temperature.
  • Powered by the serpentine belt: That winding belt under your hood is responsible for powering many crucial components, including your A/C compressor.

Signs of a worn compressor:

Oil or Freon leaks, noise, or erratic or no operation are indications that a compressor may need to be replaced. We can inspect your car for leaks using special refrigerant-detecting dyes and devices. Our equipment is sometimes referred to as a “sniffer.” It can detect a chemical leak even if no liquid is visible. Yes, you can say we’re pretty advanced over here.

WHAT IS AN A/C CONDENSER?

Consider it the master of turning hot refrigerant gases into liquid. The condenser is mounted at the front of most vehicles, usually in front of the radiator. Air passes through the condenser, turning the hot refrigerant gas into a condensed, cooler refrigerant liquid.

An A/C condenser is:

  • Found in front of the radiator and often referred to as a mini-radiator
  • The master refrigerant cooler. And still champion. The Condenser radiates the hot refrigerant gases that have entered from the compressor, reducing its temperature and pressure, turning it into a liquid that moves on to the A/C Dryer.

Signs of a worn condenser:

Leaks

Clogged, corroded or damaged fins or tubes

Poor air conditioning performance

WHAT’S A RECEIVER/DRYER?

The receiver or dryer is found on vehicles with a thermal expansion valve. It’s the safety net responsible for trapping all harmful debris, moisture, and liquids from reaching the compressor and other vital A/C parts.

The roles of the receiver/dryer:

  • Separates gas from liquid. If liquid isn’t contained in the dryer, it can enter and destroy your compressor (Compressors aren’t designed to handle liquids. Only gas).
  • Removes moisture. To trap moisture, a desiccant is used. Desiccant is similar to those moisture killing packets you find in the packaging of new electronic devices.
  • Filters out contaminants. No one wants a contaminated A/C system. Contaminants can lead to accelerated parts wear and damaging corrosion.

Quick fact: If there’s any moisture present in your compressor, it can mix with the Refrigerant and create very damaging corrosive acids.

Symptoms of a worn receiver/dryer:

  • Poor air conditioner performance
  • Moisture on glass and/or inability of defroster to remove moisture from glass and windows

The receiver/dryer must be replaced in the following situations:

  • Anytime the A/C system is opened for repair, the receiver/dryer will need to be replaced.
  • Whenever a technician has determined moisture or debris has permanently damaged your receiver/dryer performance.

WHAT IS AN ACCUMULATOR?

An accumulator is similar to a receiver-dryer, but only found on vehicles with an orifice tube. If you have an accumulator, that means you don’t have a thermal expansion valve.

The accumulator:

  • Monitors and controls the amount of refrigerant that enters the evaporator.
  • Store excess Refrigerant so that it cannot enter and damage the compressor.
  • Filters debris and removes moisture from the A/C System.

When to replace the accumulator:

  • Anytime the A/C system is opened for repair, the accumulator will need to be replaced.
  • Whenever a technician has determined moisture or debris has permanently damaged your accumulator’s performance.

WHAT IS A THERMAL EXPANSION VALVE/ORIFICE TUBE?

The orifice tube or thermal expansion valve is located between the condenser and the evaporator. Its job is to constantly monitor the pressure and temperature of your A/C system in order to determine the exact amount of refrigerant that can safely enter your evaporator. An orifice tube may also contain a fine mesh screen to block contaminants from the rest of the system.

Quick fact: If too much or too little refrigerant enters the evaporator, you could have a big problem on your hands. The proper function of the thermal expansion valve or orifice tube is crucial for successful A/C system operation.

Signs of a worn orifice tube or thermal expansion valve:

  • Poor A/C system performance
  • When a technician has determined it has become dirty or clogged

WHAT IS AN EVAPORATOR?

The evaporator is responsible for cooling air and removing moisture. If cold, refreshing air is hitting your face, your evaporator is working like a champ.

The evaporator:

  • Located right behind your dash. The evaporator is the last and most important stop before cold air can hit your face.
  • Cools air with refrigerant. Low pressure Refrigerant travelling through the evaporator absorbs heat from the passenger compartment dropping the temperature of the evaporator. Air blown over the cool surface of the evaporator then comes out the vents providing the chill you expect.
  • Commences cold air flow. The best and final stage. Cold air should now be blowing out your vents thanks to the hard work of the evaporator.

Symptoms of a worn evaporator:

  • Poor A/C system performance

WHAT IS A COMPRESSOR CLUTCH?

Before the compressor turns on, a special electro-magnetic clutch, conveniently called the “compressor clutch,” is necessary to engage and disengage the compressor cycle. The compressor clutch tells the compressor when to turn on or off so that the Freon (refrigerant) is correctly pressurised for use by the condenser which is then delivered to the evaporator where the chill begins.

WHAT IS THE CLUTCH CYCLING SWITCH?

The clutch cycling switch senses and controls the temperature in the evaporator core to prevent it from freezing. Although most cars can blow air at temperatures as low as 60 degrees, the temperatures inside the evaporator core can get cold enough to completely freeze the entire core. Not good! The clutch cycle’s job is to make sure the evaporator temperature doesn’t reach the point of glacier temperatures.

Symptoms of a failing clutch cycling switch:

  • Evaporator freezing up
  • Evaporator does not get cold enough

WHAT IS A REFRIGERANT CHARGE PORT?

This is where the magic happens. The refrigerant charge port is the connection point where new refrigerant can enter the system during an A/C system recharge. Your port is usually located on the bigger A/C hose near or on the accumulator.

Caution: Only properly equipped and qualified persons should perform A/C recharging service
We hope you found this article interesting and helpful in regard to the parts of an air conditioning unit. Remember to get your air conditioning serviced by a qualified mechanic.

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