Receiver Drier with leaks - Rare in the drier itself but can occur at welds, joints. Can also occur at fittings, usually due to bad installation.

Receiver Drier with Rust or corrosion - Caused by contamination in system or inadequate evacuation, leaving moisture in the system.

Receiver Drier with Filter/desiccant breakdown - This problem is unusual but occurs occasionally, especially if the drier is incorrectly installed in reverse.

Receiver Drier with Blockage - May be caused by rust/corrosion, desiccant breakdown, or contamination from other failed components such as compressors.

Receiver Drier installed Incorrectly - Receiver-driers can be installed in reverse. This results in vapour passing to the TX valve instead of liquid, causing a considerable drop in performance at the evaporator.

Receiver Drier Installed too close to heat source - Receiver-driers should always be installed as far away from the engine and manifold as possible. Some receiver-driers will release some of the moisture they have absorbed if they get too hot.

Important notes

Both the filter and the desiccant in a receiver-drier have limitations and a limited life. The desiccant, whether molecular sieve or silica-gel, can only absorb a small amount of moisture. The filter will not remove 100% of all particles and foreign material.

Receiver-driers are not a substitute for proper flushing or evacuation.

Receiver-driers cannot be evacuated. They must be replaced at regular intervals (often recommended at about every 2 years), whenever system contamination occurs, or whenever the system is open to the atmosphere.

Diagnosis Tips

  • Leaks are often visible due to oily patches.
  • Blockages and severe restrictions at the inlet are indicated by high head pressures.
  • Blockages and restrictions at the outlet are indicated by low pressure readings on both gauges.
  • Blockages can usually be detected by feeling for hot and cold spots.
  • Because of variations in condensing conditions in automotive air-conditioning systems, occasional bubbles in the sight glass are quite normal and do not necessarily indicate insufficient refrigerant charge, especially with R134a (with R134a the sight glass if fitted may look cloudy but still be normal.)
  • Always charge a system by refrigerant volume, gauge readings and evaporator coil temperature. Refer to the Temperature – Pressure charts.
  • Where sight glasses are fitted, they are a guide to flow and bubbles which may indicate low refrigerant with some refrigerants.