When a car AC receiver-drier (or accumulator) fails, the most common symptom is that the air conditioning stops cooling or its cooling performance drops significantly. This is often accompanied by moisture in the sight glass and abnormal temperature differences in the piping. Here are the main symptoms:

Significantly reduced cooling: The air from the vents isn't cold and might even blow hot air. This is especially noticeable after the car has been parked in the sun.

Abnormal sight glass: Moisture, cloudiness, bubbles, or oil stains appear in the top observation window.

Large temperature difference in the pipes: If you touch the upper and lower pipes connected to the receiver-drier and feel a noticeable temperature difference, it indicates an internal blockage.

Abnormal frost formation: Uneven frosting on the receiver-drier or the condenser surface.

Unusual noises and frequent cycling: A rattling or sloshing sound from the system, along with the compressor frequently turning on and off as a protective measure.

What happens if it gets blocked?

Dual-low pressure readings: Both the high-side and low-side gauges will show low pressure.

Refrigerant circulation: The refrigerant flow is obstructed. If left untreated for a long time, it can corrode the pipes and damage the compressor.

Symptoms can vary depending on the vehicle model, so it's best to confirm with a pressure test. It is recommended to take the car to a professional repair shop for inspection and replacement.