How Does Air Get Into an AC System?

Air gets into an AC system primarily through leaks, especially on the low-pressure side of the refrigerant system.

The Mechanics of Air Intrusion

When the refrigeration system has a leak, it creates a pressure imbalance. Here’s a breakdown:

Refrigerant Leaks: Small leaks in the AC system allow refrigerant to escape over time.
Undercharged System: As refrigerant leaks out, the system becomes undercharged.
Vacuum Creation: A severely undercharged system can create a vacuum, particularly on the low side. This vacuum sucks in air from the surrounding environment through any existing leaks. According to the provided reference, "Severely undercharged systems will run vacuums in the low side".

In essence, a leak acts as an entry point, and the pressure difference draws air into the system.

Leaks can occur at various points in the AC system:

Fittings: Connections between different components can loosen or corrode.
Hoses: Rubber hoses can crack or degrade over time.
Seals: Seals around the compressor and other components can fail.
Evaporator and Condenser Coils: These coils are susceptible to corrosion and damage from debris.

Air contamination within an AC system can lead to several issues:

Reduced Cooling Efficiency: Air displaces refrigerant, decreasing the system's ability to cool effectively.
Increased Pressure: Air raises the system's operating pressure, potentially causing damage to components.
Corrosion: Moisture in the air can lead to internal corrosion.
Compressor Damage: Overheating and lubrication issues can damage the compressor.

Addressing air in the AC system typically involves:

Leak Detection: Identifying and repairing all leaks is the first step.
System Evacuation: Removing the air and any remaining moisture using a vacuum pump.
Recharging: Properly recharging the system with the correct amount of refrigerant.