Compression Ratio Exceeded
refrigeration
Description
Compressor compression ratio is greater than 21 for 20 seconds; engine operation shuts down the engine and unit with an alarm, and electric operation shuts refrigeration with PSCON energized.
Activation Conditions
If the compressor compression ratio is greater than 21 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 21 for 3 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. There can be 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 8.4.10 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 Trouble Shooting Section 8.4.8.