Diagnose by Symptom
No code on the display — start from what you see
If your unit is failing but no specific code appears, pick the symptom that best matches what's happening. We'll show every Thermo King, Carrier, Danfoss, Copeland and Bitzer code that points to that issue.
Reefer, walk-in cooler, freezer or commercial unit running but failing to reach setpoint. Fault codes related to insufficient cooling, temperature deviation, or warm box alarms.
Compressor not starting, short cycling, overheating, low oil pressure or contactor failure. Codes that point to compressor lockout or protection trips.
System showing low refrigerant charge, suction pressure too low, or refrigerant leak alarms. Common in R-404A, R-452A, R-134a and R-744 systems.
Temperature probe, return-air sensor, ambient sensor or pressure transducer reading out of range, open or shorted. Sensor swap is often the fastest fix.
Diesel engine cranking but not starting, fuel system faults, low oil, low coolant or starter circuit issues on Thermo King and Carrier Transicold transport units.
Defrost cycle not initiating, terminating early, or evaporator iced over. Often a defrost termination switch, heater or timer fault.
Battery voltage out of range, alternator not charging, blown fuse, shorted harness, or contactor/relay failures.
Fan motor not running, locked rotor, overcurrent on evaporator or condenser fans, or airflow alarms.