In this article, we’re diving into Common Refrigeration System Failures and How to Fix Them. Whether you’re troubleshooting in the field or trying to prevent costly downtime, understanding these failures is critical.”
1. Compressor Burnout – Causes & Symptoms
First on the list — compressor burnout. This is one of the most catastrophic failures in a refrigeration system. A burnout occurs when internal motor windings overheat and break down, releasing acids into the system.
Common Causes:
Loss of Lubrication.
Lubrication is often lost due to refrigerant leaks or flooding that washes oil out of the compressor, leading to metal-on-metal contact and eventual burnout.
Electrical Issues
(like voltage imbalance or short circuits). Short circuits in a compressor typically occur when insulation on the motor windings breaks down due to overheating, moisture, or age, causing electrical contact between phases or to ground.
Overheating due to poor cooling or airflow issues.
Overheating due to poor cooling or airflow occurs when dirty condenser coils, blocked airflow, or failed condenser fans prevent proper heat rejection, causing the compressor to run hot and eventually fail.
Pro Tip:
Always check the compressor oil for acid when replacing a burnt-out compressor.
2. TXV Failure – Starving or Flooding the Evaporator
The Thermostatic Expansion Valve, or TXV, regulates the flow of refrigerant into the evaporator. When it fails, it can either starve the evaporator—leading to high superheat—or flood it, which risks damaging the compressor.
Common Causes:
- Contaminants blocking the orifice
- Bulb sensing line losing charge
- Over-tightened superheat adjustment
Pro Tip:
Check superheat and subcooling readings to diagnose valve performance.
3. Low Refrigerant Charge – Leaks or Undercharging
A low charge condition reduces system efficiency and can result in coil icing and compressor overheating. This often stems from small leaks over time or improper charging during service.
Common Signs:
Low Suction Pressure.
Low refrigerant charge causes low suction pressure because there’s insufficient refrigerant evaporating in the coil, resulting in less vapor returning to the compressor and thus lower pressure in the suction line.
High Superheat.
Low refrigerant charge causes high superheat because there isn’t enough refrigerant to fully saturate the evaporator coil, so the remaining vapor continues to gain heat, raising the superheat temperature.
Ice Buildup on Evaporator.
Ice builds up on a coil with low refrigerant charge because the reduced pressure lowers the refrigerant’s boiling point, causing the coil temperature to drop below freezing and moisture in the air to freeze on the surface.
Pro Tip:
Always pressure test and use nitrogen before vacuum and charging.
4. Restrictions – Blocked Flow in the Refrigerant Circuit
Restrictions in the refrigerant circuit choke the system, leading to high subcooling and starving of the evaporator. A common culprit is a blocked filter drier or debris at the TXV inlet screen.
How to Diagnose:
Temperature drop across the component. A normal temperature drop across a component like a filter drier is minimal—typically 1°F or less—while an abnormal drop, such as 3°F or more, indicates a restriction or blockage that’s impeding refrigerant flow.
High subcooling + low suction pressure.
In an R32 system for example, high subcooling—such as 20°F or more—combined with low suction pressure—like 80 psi or lower (when 120–135 psi would be normal), typically indicates a restriction in the liquid line, such as a clogged filter drier or TXV, causing liquid refrigerant to back up before the restriction and starving the evaporator.
Pro Tip:
Use temperature clamps and feel for a temp drop across suspect component.
5. Non-Condensables – Air or Contaminants in the System
Air or non-condensable gases can be accidentally introduced during poor evacuation or improper charging. This leads to high head pressure and poor heat rejection at the condenser.
Symptoms:
Higher than Normal Head Pressure.
Non-condensables like air or nitrogen in the system do not condense in the condenser, so they take up space and reduce heat transfer efficiency, causing the head pressure to rise above normal operating levels.
Low System Capacity.
Non-condensables reduce system capacity by displacing refrigerant volume and impairing heat transfer in the condenser, resulting in less effective cooling and lower overall system performance.
Pro Tip:
Always evacuate with a micron gauge to below 500 microns before charging.
6. Electrical Failures – Faulty Components
From bad contactors to failed capacitors and sensors, electrical failures can take down an otherwise healthy refrigeration system. Always inspect for loose terminals and degraded wiring.
Common Causes:
Power Surges.
Power surges happen when there’s a sudden spike in voltage—often caused by lightning strikes, utility grid switching, or large equipment cycling—which can damage sensitive electrical components in the system.
Over-amped Components.
Overamped components occur when motors or electrical parts draw more current than designed, often due to mechanical binding, low voltage, or internal faults, leading to overheating and potential failure.
Poor Maintenance.
Poor maintenance causes electrical failures by allowing dust, corrosion, loose connections, or worn components to go unnoticed, leading to overheating, arcing, and eventual breakdown of electrical parts.
Pro Tip:
Use a clamp meter and megohmmeter for thorough electrical diagnosis.
SUMMARY
Let’s recap — compressor burnout, TXV issues, low charge, restrictions, non-condensables, and electrical failures are the most common refrigeration system problems. Diagnosing them early can save time, money, and system longevity.
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