With daily highs reaching at least the mid-90s, you’ve probably already been blasting your car’s A/C for weeks. Do you know how your car manages to cool 90-something degree air to a temperature that keeps you from being a sopping wet mess by the time you get from Point A to Point B? It really only takes five components.
While it may be 90-something outside, your A/C system isn’t using outside air to cool your car. Rather, the whole cooling process starts with gas refrigerant (usually Freon R-134a), which is compressed by a pump powered by an engine belt. Compressing gas creates a lot of heat and pressure. Seems counterintuitive, right?
The pressurized gas refrigerant is pushed to the condenser, where it loses some heat—enough for the refrigerant to convert from a gas to a liquid.
Before moving any further through the air conditioning system, the hot liquid refrigerant goes through a drier where desiccants (like those little silica packets in new shoes) collect any water that may have entered the system. It’s important to remove any water before the actual cooling begins so that ice doesn’t form inside any of the tubes or coils, which could damage the system.
Thermal Expansion Valve
Once the water-free refrigerant hits the thermal expansion valve, the liquid is allowed to expand, which allows for a dramatic decrease in temperature. The valve controls the level of refrigerant allowed to move on to the evaporator, which controls how cool your car feels.
In the evaporator coils, the liquid refrigerant, which is at or near the freezing point of water (32°F, 0°C), is allowed to warm up and expand into gas form, a form that absorbs a lot of heat (the scientific explanation for cooling). The cool air that surrounds the refrigerant-filled coils is blown into your car by a fan, which you control, too.
That’s it! That’s the complete cycle of the refrigerant in your car’s A/C system that keeps you cool no matter how hot it is outside. Unless, of course, your A/C needs recharging (flushing out old refrigerant and filling with new). If your A/C system does need to be recharged, it’s highly recommended to take your car to a shop so that the old refrigerant can be properly disposed of. A trained technician can also check for any leaks that may have led to low refrigerant levels to begin with.