Reefer Alarm Code Guide
If your reefer display is showing a flashing alarm right now, this guide gives you a fast read on what it likely means.
Tell us your location, unit brand, set point and current reading — we load the truck before the tech leaves.
Alarm codes exist to warn you before small problems become expensive ones. A red alarm on Thermo King, or a fault code on Carrier, means the system detected something outside safe operating range.
Common Thermo King Alarms
- High discharge pressure, often linked to a dirty condenser coil or low airflow
- Low refrigerant pressure, usually a sign of a leak
- Engine oil pressure fault, which can point to a serious mechanical issue
- Battery voltage fault, often an early sign of charging system trouble
Common Carrier Alarms
- Sensor faults affecting temperature readings
- High and low pressure alarms tied to refrigerant charge
- Engine and fuel system faults
- Electrical faults affecting startup or run time
Reading the code is only the first step. The code tells you the symptom the system detected, not always the root cause. A pressure alarm, for example, could come from low refrigerant, a blocked coil, or a failing fan, and telling those apart usually needs a gauge set and hands on testing.
Clearing an alarm without fixing what caused it almost always means it comes back, often at a worse time than the first one.
If you're staring at an alarm code right now, call 972-703-4445 and read it to us. We'll tell you what it likely means and send a tech to your location anywhere in Dallas-Fort Worth.
If this is happening right now
This guide explains the problem. These pages cover the repair itself.