Mechanical Diagnostics
| Condition | Possible Cause | Remedy |
|---|---|---|
| Compressor does not operate - no amperage draw. | Controller on; unit start sequence still timing. | Wait up to two minutes for compressor start-up. |
| No power to unit (condenser and evaporator fans do not operate). | Locate fault and repair: power source, power plug, CB1 main circuit breaker, motor solid state, motor terminals, motor, fuses on power module. | |
| Open in 29 Vac control circuit. | Check fuses and On/Off switch. Replace or repair as required. | |
| Container temperature does not demand compressor operation. | Adjust controller setpoint. | |
| Compressor contactor inoperative. | Replace compressor contactor. | |
| No output signal from controller. | Diagnose and replace power module or controller. | |
| Unit on defrost. | Turn Unit On/Off switch Off and then On again. | |
| Detective high pressure or low pressure cutout switch. | Replace defective switch. | |
| High condenser head pressure causing high pressure cutout. | Check refrigeration system and correct fault. | |
| Defective compressor. | Replace compressor. | |
| Controller shut unit down on Compressor Over Temperature. | Let compressor cool and controller will reset automatically. Check vapor injection valve and compressor temperature sensor. | |
| Compressor motor internal thermal overload protection open. | If compressor contactor is energized, wait 60 minutes for protector to cool and reset. | |
| Compressor does not operate - excessive amperage draw or intermittent cycling on overload. | Rotating scroll stuck. | Replace compressor. |
| Seized or frozen compressor bearings. | Replace compressor. | |
| Improperly wired. | Check/correct wiring against wiring diagram. | |
| Low line voltage. | Check line voltage - determine location of voltage drop. | |
| Contacts in compressor contactor not closing completely. | Check by operating manually. Repair or replace. | |
| Open circuit in compressor motor winding. | Check motor stator connections. Check stator winding for continuity. If open, replace compressor. | |
| Defective compressor motor internal thermal overload protector. | Replace thermal overload protector or compressor. | |
| Refrigerant overcharge or high side restriction causing cycling on high pressure cutout. | Check for restricted filter drier, in-line filter or high side; or refrigerant overcharge. | |
| Inefficient condenser operation causing cycling on high pressure cutout. | Check condenser airflow, condenser fan motor, fan blade, condenser grille, condenser coil temperature sensor, water pressure switch (option), water flow rate (option) and water-cooled condenser-receiver tank (option). | |
| Compressor contactor burned out. | Low line voltage. | Increase line voltage to at least 90 percent of compressor motor rating. |
| Excessive line voltage. | Reduce line voltage to at least 110 percent of compressor motor rating. | |
| Short cycling. | Eliminate cause of short cycling. | |
| Unit short cycles. | Refrigerant overcharge causing cycling on high pressure cutout. | Purge system. |
| Inefficient condenser operation causing cycling on high pressure cutout. | Check condenser airflow, condenser fan motor, condenser fan grille, condenser fan pressure switch, water pressure switch (option), water flow rate (option) and water-cooled condenser-receiver tank (option). | |
| Noisy compressor | Loose mounting bolts. | Tighten mounting bolts. |
| Oil slugging or refrigerant flooding back. | Perform controller pretrip test to check refrigerant charge. Check expansion valve adjustment. Check compressor for compressor oil. | |
| Scroll rotating backwards. | Check phase correction system and check unit wiring. | |
| Defective compressor. | Repair or replace compressor. | |
| Condenser fan motor does not operate. | Unit in Heat or Defrost. | Check indicator. If unit is in Heat or Defrost, unit operation is normal (no remedy required). |
| Unit in Cool with low condenser temperature. | Check indicator condenser temperature and discharge pressure. Condenser temperature may not require condenser fan operation (no remedy required; condenser fan also pulses on and off on a 30 second cycle to control condenser temperature). | |
| Water pressure switch closed (Water-cooled position) (Option). | If unit is on water cooled condenser operation, unit operation is normal. Otherwise water pressure switch must be Open for air-cooled condenser operation. | |
| Defective water pressure switch (option). | Replace defective switch. | |
| Loose line connection. | Tighten connections. | |
| Open motor internal thermal overload protector. | Check for seized bearings or defective thermal overload protector. Repair or replace as necessary. | |
| Defective motor. | Replace motor. | |
| Detective condenser fan contactor. | Replace defective contactor | |
| No condenser fan output signal from controller. | Diagnose and replace condenser fan relay, power module or controller. | |
| Evaporator fan motor(s) does not operate. | Unit on defrost. | Check operating mode indicator LEDs. |
| Loose line connection. | Tighten connections. | |
| Open motor internal thermal overload protector. | Check for seized bearings or defective thermal overload protector. Repair or replace as necessary. | |
| Defective motor. | Replace motor. | |
| No low or high speed evaporator fan output signal from controller output module. | Diagnose and replace output module or controller. |
| Condition | Possible Cause | Remedy |
|---|---|---|
| Compressor does not operate - no amperage draw. | Controller on; unit start sequence still timing. | Wait up to two minutes for compressor start-up. |
| No power to unit (condenser and evaporator fans do not operate). | Locate fault and repair: power source, power plug, CB1 main circuit breaker, motor contactors, motor terminals, motor. | |
| Open in 29 Vac control circuit. | Check fuses and On/Off switch. Replace or repair as required. | |
| Container temperature does not demand compressor operation. | Adjust controller setpoint. | |
| Compressor contactor inoperative. | Replace compressor contactor. | |
| No output signal from controller. | Diagnose and replace power module or controller. | |
| Unit on defrost. | Turn Unit On/Off switch Off and then On again. | |
| Detective high pressure or low pressure cutout switch. | Replace defective switch. | |
| High condenser head pressure causing high pressure cutout. | Check refrigeration system and correct fault. | |
| Defective compressor. | Replace compressor. | |
| Controller shut unit down on Compressor Over Temperature. | Let compressor cool and controller will reset automatically. Check vapor injection valve and compressor temperature sensor. | |
| Compressor motor internal thermal overload protection open. | If compressor contactor is energized, wait 60 minutes for protector to cool and reset. | |
| Compressor does not operate - excessive amperage draw or intermittent cycling on overload. | Rotating scroll stuck. Piston Stuck. |
Replace compressor. |
| Seized or frozen compressor bearings. | Replace compressor. | |
| Improperly wired. | Check/correct wiring against wiring diagram. | |
| Low line voltage. | Check line voltage - determine location of voltage drop. | |
| High head pressure | Eliminate cause of high head pressure. | |
| Contacts in compressor contactor not closing completely. | Check by operating manually. Repair or replace. | |
| Open circuit in compressor motor winding. | Check motor stator connections. Check stator winding for continuity. If open, replace compressor. | |
| Defective compressor motor internal thermal overload protector. | Replace thermal overload protector or compressor. | |
| Refrigerant overcharge or high side restriction causing cycling on high pressure cutout. | Check for restricted filter drier, in-line filter or high side; or refrigerant overcharge. | |
| Inefficient condenser operation causing cycling on high pressure cutout. | Check condenser airflow, condenser fan motor, fan blade, condenser grille, condenser coil temperature sensor, water pressure switch (option), water flow rate (option) and water-cooled condenser-receiver tank (option). | |
| R 23 compressor not running | Auxiliary contact on R134a open | Check curcuit, replace contact. |
| Compressor contactor burned out. | Low line voltage. | Increase line voltage to at least 90 percent of compressor motor rating. |
| Excessive line voltage. | Reduce line voltage to at least 110 percent of compressor motor rating. | |
| Short cycling. | Eliminate cause of short cycling. | |
| Unit short cycles. | Controller out of calibration | Check controller software program version; load new software in controller and recheck unit performance, replace controller |
| Refrigerant overcharge causing cycling on high pressure cutout. | Purge system. | |
| Inefficient condenser operation causing cycling on high pressure cutout. | Check condenser airflow, condenser fan motor, condenser fan grille, condenser fan pressure switch, water pressure switch (option), water flow rate (option) and water-cooled condenser-receiver tank (option). | |
| Noisy compressor | Insufficient compressor oil | Check compressor oil level on R-134a and R-23 system. Add oil to proper level. |
| Loose mounting bolts. | Tighten mounting bolts. | |
| Oil slugging or refrigerant flooding back. | Perform controller pretrip test to check refrigerant charge. Check expansion valve adjustment. Check compressor for compressor oil. | |
| Scroll rotating backwards. | Check phase correction system and check unit wiring. | |
| Worn fan motor bearings | Replace bearings or motor. | |
| Defective compressor. | Repair or replace compressor. | |
| Condenser fan motor does not operate. | Unit in Heat or Defrost. | Check indicator. If unit is in Heat or Defrost, unit operation is normal (no remedy required). |
| Loose line connection. | Tighten connections. | |
| Open motor internal thermal overload protector. | Check for seized bearings or defective thermal overload protector. Repair or replace as necessary. | |
| Defective motor. | Replace motor. | |
| Detective condenser fan contactor. | Replace defective contactor | |
| No condenser fan output signal from controller. | Diagnose and replace condenser fan relay, power module or controller. | |
| Evaporator fan motor(s) does not operate. | Unit on defrost. | Check operating mode indicator LEDs. |
| Loose line connection. | Tighten connections. | |
| Open motor internal thermal overload protector. | Check for seized bearings or defective thermal overload protector. Repair or replace as necessary. | |
| Defective motor. | Replace motor. | |
| Defective low speed evaporator fan contactor | Replace defective contactor | |
| No low or high speed evaporator fan output signal from controller output module. | Diagnose and replace output module or controller. |