Why Is There Ice Buildup on My Evaporator Coils?
Nov 25, 2025
Ice forms on evaporator coils when airflow, refrigerant levels, or defrost cycles are disrupted, causing coil temperatures to drop below freezing.
Evaporator coil icing is a common commercial refrigeration issue that occurs when heat cannot transfer properly through the system. Restricted airflow, low refrigerant pressure, excess moisture, or defrost failures can all cause coils to freeze, leading to rising temperatures, strained equipment, and potential product loss if not corrected quickly.
What Causes Ice To Build Up on Evaporator Coils?
Evaporator coils remove heat from inside coolers and freezers. When operating conditions fall outside normal ranges, moisture in the air freezes on the coil surface instead of draining away. Below are the most common causes, ordered from operational issues to mechanical failures.
Common Causes of Ice Buildup on Evaporator Coils
1. Restricted Airflow
Evaporator coils require steady airflow to absorb heat efficiently. When airflow is blocked, coil temperatures drop too low, allowing moisture to freeze.
2. Dirty or Clogged Evaporator Coils
Grease, dust, and debris act as insulation on coil surfaces. This reduces heat transfer and forces the system to operate colder than designed, increasing the likelihood of ice formation.
3. Low Refrigerant Levels
When refrigerant levels drop, pressure inside the evaporator coil decreases. Lower pressure causes refrigerant temperatures to fall below normal operating ranges, freezing condensation on the coil. Low refrigerant almost always indicates a leak that requires professional repair.
4. Faulty or Obstructed Evaporator Fans
Evaporator fans move air across the coils. If a fan motor is failing or blades are coated with debris, airflow slows and ice begins forming at the coldest points first.
5. Door Seal Failures and Excess Door Openings
Warm, humid air entering the unit condenses when it contacts cold surfaces. Damaged gaskets, misaligned doors, or frequent access dramatically increase moisture load and accelerate icing.
6. Defrost Cycle or Thermostat Malfunctions
Commercial systems rely on scheduled defrost cycles to clear frost before it accumulates. If defrost heaters, timers, sensors, or thermostats fail, ice builds faster than it can melt.
Evaporator Coil Icing: Cause vs. Impact
| Issue | What Happens | Operational Risk | Professional Repair Needed? |
|---|---|---|---|
| Blocked airflow | Coils run too cold | Rising cabinet temps | Sometimes |
| Dirty coils | Reduced heat transfer | Higher energy use | Recommended |
| Low refrigerant | Pressure drops, icing accelerates | Compressor damage | Yes |
| Fan failure | Uneven cooling | Product spoilage | Yes |
| Defrost failure | Ice accumulates rapidly | System shutdown | Yes |
How To Troubleshoot Evaporator Coil Ice Safely
If ice buildup is visible, limited troubleshooting can be performed without risking equipment damage. Avoid scraping or chipping ice, which can puncture coils or refrigerant lines.
Power Down and Allow a Full Defrost
Turn the unit off and allow ice to melt naturally. Depending on severity, defrosting may take several hours. Plan for temporary product relocation if necessary.
Protect the Coil Surface
Tip: Never use sharp tools or heat sources on evaporator coils—physical damage can result in refrigerant leaks.
Check for Airflow Obstructions
Inspect vents, evaporator covers, and fan areas for boxes or containers that may be blocking airflow—especially in high-traffic commercial coolers.
Inspect Door Gaskets and Hinges
Even minor air leaks introduce moisture that contributes to icing. Worn, cracked, or loose gaskets should be replaced promptly.
Confirm the Condenser Is Clean
While icing occurs at the evaporator, a dirty condenser can destabilize system pressures and temperatures, increasing the risk of coil freeze-ups.
When To Call a Commercial Refrigeration Professional
If ice returns shortly after defrosting or temperatures fluctuate despite clear airflow, professional service is required. Ongoing icing often signals deeper mechanical or control issues, including:
RBAir provides expert commercial refrigeration services, including diagnostics, repairs, and preventive maintenance programs designed to minimize downtime and protect inventory.
Need Fast Commercial Refrigeration Repair?
Our technicians can diagnose evaporator coil issues and restore proper cooling before product loss occurs.
How To Prevent Evaporator Coil Ice Buildup
Preventive maintenance is the most effective way to avoid recurring coil icing and extend equipment life in commercial environments.
Your Commercial Refrigeration System Shouldn’t Struggle With Ice
Ice buildup on evaporator coils is common—but it’s never normal. Addressing airflow, cleanliness, and mechanical issues early helps maintain stable temperatures, reduce energy strain, and prevent costly downtime.
If your system experiences recurring icing or inconsistent cooling, RBAir is ready to help with reliable commercial refrigeration diagnostics and repair.
Ready To Resolve Evaporator Coil Icing?
We’ll identify the cause of ice buildup and restore efficient, reliable cooling.