Car AC Maintenance Tips

After the summer heat is over, most people forget about their Car AC until next year. Here are some things you can do in the off-season to keep your AC working it’s best!

  • Run the air conditioner once a week for about 10 minutes. This will maintain gas pressure to keep the compressor working properly, and keep your AC system’s seals working. When you do this, be sure to turn it to its highest fan speed and coolest setting.
  • Run defrost mode for a few minutes. This prevents mildew and cleans out excessive moisture, which can lead to unsavory odors in your car.
  • Use your air conditioner in winter. In addition to cooling your vehicle, one of the air conditioner’s primary functions is to remove humidity from the cabin. It works especially well when you need to remove fog from the windshield to improve visibility.
  • Recharge the system – Your car’s AC should be evacuated and recharged about every 2 years to keep the refrigerant & oil levels correct.
  • Cabin Air Filter Replacement – In addition to making the air in your car better for you, it makes the air better for your car’s HVAC system as well! This air filter traps dust and debris so other components like your blower motor, heater core, and evaporator core stay clean and the air is able to flow through them efficiently.

How Does my Car AC Work?

Your car AC system consists of an A/C Condenser, which can be found in front of the radiator, an A/C Compressor, which is attached to the engine, an evaporator core, which is behind your dashboard, an Orifice Tube or Thermal Expansion Valve, a Reciever/Dryer, and some plumbing. All of this is filled with a refrigerant gas, which is what actually cools the air, and an oil, which is dispersed in the gas to lubricate the inside of the system.

System Components:

The A/C Compressor, as the name suggests, is a pump. It’s attached to your engine’s crankshaft by a belt, and uses a small amount of engine power to turn the pump and compress the refrigerant gas to help turn it into a liquid.

The A/C Condenser is like a radiator. It sits in front of your actual radiator, near the front of the car. The refrigerant enters the condenser as a pressurized gas from the compressor. The process of pressurizing the gas and moving it to the condenser creates heat, but the airflow through the condenser removes that heat until the gas becomes a liquid.

The Receiver/Dryer is the next stop for the refrigerant. It receives the now-liquid refrigerant, and moves it through a dessicant (like the silica gel packets you typically find in a box of new shoes) to remove any water that has found it’s way into the system.

The Thermal Expansion Valve or Orifice Tube is a restriction placed in the line after the Reciever/Dryer, just before the Evaporator Core. It’s an intentional restriction in the line that reduces the pressure on the liquid refrigerant so it’s ready to turn back into a gas. Sort of like what happens to the butane inside a BIC lighter when you press the thumb paddle.

The Evaporator Core is where the magic happens. It also looks like a radiator, with its coil of tubes and fins, but its job is to absorb heat rather than dissipate it. Refrigerant enters the evaporator coil as a cold, low-pressure liquid, ideally at 32 degrees Fahrenheit (0 degrees Celsius), which is why you don’t want any water in the system. The refrigerant doesn’t freeze at this temperature, but it does have a very low boiling point. The heat in the cabin of the car is enough to make the R-134a in the evaporator boil and become a gas again, just like water turning back to steam. In its gaseous form, refrigerant can absorb a lot of heat. The blower motor pushes air through the evaporator core, which cools the air, then through the evaporator box and out of the vents.

From there, the refrigerant flows back to the A/C Compressor so the cycle can continue indefinitely.

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