Refrigeration System Ice Blockage: Causes & Solutions

Ice blockage is one of the most common and troublesome faults in refrigeration systems. When it occurs, the system cooling capacity drops sharply, compressor load increases, and in severe cases, the compressor may burn out. This article analyzes the formation mechanism of ice blockage, prevention measures, and the critical role of filter dryers in preventing ice blockage.

I. What is Ice Blockage?

Ice blockage refers to the phenomenon where moisture in the refrigeration system freezes at the expansion device or capillary tube, forming ice crystals that block refrigerant flow. This causes:

• Reduced or completely stopped refrigerant circulation
• Decreased cooling capacity, unable to reach target temperature
• Increased compressor load, higher power consumption
• Compressor overheating, potentially leading to burnout
• Cyclic on/off operation (cooling then stopping repeatedly)

II. Root Causes of Ice Blockage

1. Moisture Entering the System

This is the primary cause of ice blockage. Moisture can enter through:

• Improper vacuum evacuation during installation or maintenance
• Leakage in system piping or connections
• Using refrigerant or lubricating oil with high moisture content
• Opening the system in humid environments during maintenance
• Compressor motor burnout producing moisture

2. Insufficient or Failed Filter Dryer

If the filter dryer's desiccant is saturated or the filter itself is damaged, it cannot effectively remove moisture, leading to gradual accumulation and eventual ice blockage.

3. Contaminants in the System

Oxide particles, metal shavings, welding slag, and other solid impurities can accumulate at narrow passages, forming nucleation sites where ice crystals easily form.

III. Prevention Measures

1. Strict Vacuum Evacuation

After installation or maintenance, the system must be vacuum evacuated to below 500 microns (0.67 mbar) and held for at least 30 minutes. Use a high-quality vacuum pump and digital vacuum gauge for accurate measurement.

2. Install a High-Quality Filter Dryer

Select a filter dryer with sufficient moisture absorption capacity and replace it regularly (every 1-2 years). The KLD series uses an 80% molecular sieve + 20% activated alumina composite formula with superior moisture absorption performance.

3. System Leak Testing

After installation, perform nitrogen pressure testing (at least 1.5 times working pressure) and use electronic leak detectors or soap bubble testing to ensure no leaks.

4. Use High-Purity Refrigerant

Purchase refrigerant from reputable manufacturers and avoid using recycled refrigerant with unknown moisture content. New refrigerant moisture content should be below 10 ppm.

5. Avoid Opening System in Humid Conditions

When maintenance requires opening the system, choose low-humidity weather or use nitrogen purging to minimize moisture entry.

IV. How to Handle Ice Blockage

If ice blockage has already occurred, follow these steps:

1. Stop the system — Do not continue running to avoid compressor damage
2. Thaw naturally — Allow the system to warm up naturally, ice will melt (do not use open flame)
3. Replace the filter dryer — This is critical. The old filter is saturated and must be replaced with a new one
4. Re-evacuate — Evacuate to below 500 microns and hold
5. Recharge refrigerant — Add the correct type and amount of refrigerant
6. Monitor operation — Run for 24 hours and observe for recurrence

V. The Role of Filter Dryers in Preventing Ice Blockage

The filter dryer is the first line of defense against ice blockage. Its functions include:

• Moisture Absorption — Molecular sieve adsorbs water molecules, keeping system moisture below safe levels
• Particle Filtration — Filters solid impurities, preventing them from accumulating at narrow passages
• Acid Neutralization — Activated alumina neutralizes acidic substances, preventing corrosion
• Protecting the Expansion Device — Prevents clogging of expansion valves or capillary tubes

The KLD series filter dryer uses a proprietary molecular sieve formula with adsorption capacity 30% higher than standard products, effectively preventing ice blockage in high-moisture environments.

VI. Further Reading

• How to Choose a Filter Dryer? Complete KLD Series Selection Guide
• How Molecular Sieve Works in Refrigeration Systems
• KLD Series Filter Dryer Product Details