Compression Ratio Exceeded
refrigeration
Description
The compressor compression ratio is greater than 24 for 20 seconds; engine operation shuts down the engine and unit and alarms, and electric operation shuts down refrigeration and alarms with PSCON still energized.
Activation Conditions
If the compressor compression ratio is greater than 24 for 20 seconds.
Unit Behavior
Engine Operation: Engine and unit shutdown and alarm. Electric Operation: Refrigeration system shutdown and alarm with PSCON still energized.
Reset Conditions
Auto reset when compression ratio is less than 24 for three minutes or, alarm may be manually reset via keypad or by turning the unit off, then back on again.
Corrective Actions
1. Check for Refrigerant Overcharge - Refer to Section 8.7.2. Must be correct. 2. Check Airflow Through Radiator / Condenser Coil a. Inspect condenser / radiator fins. Fins must be straight. 90% or more of the coil surface must be undamaged. No “dead” air spaces. Condenser / Radiator coil must be clean (refer to Section 8.6.14). b. Check condenser airflow. Make sure there is even airflow through the entire coil and no “dead” spots. c. Check condenser fan rotation / operation. Fans should operate correctly. Air should be drawn in through the grill, and directed into the engine compartment. 3. Check Evaporator Section - Check evaporator section, return air bulkhead, air chute, cleanliness of evaporator coil and airflow. Refer to Section 6.4.10 4. Check System for Non-Condensables - Check refrigeration system for noncondensable gas(es). No noncondensable gas(es) may be present. Refer to Section 8.7.2. 5. Look for high discharge or low suction pressure causes - Refer to Alarm 00013 High Discharge Pressure and 00018 Low Refrigerant Pressure. Discharge and suction pressures must be in normal range for the current ambient and refrigerated compartment temperature conditions. Refer to Abnormal Pressure Troubleshooting Section 6.4.8.