Turbo Air error codes map to a few parts: E1 is the cabinet air probe, E2 is the evaporator or defrost probe, E3 is a defrost fault, and E4 is a control or regulation fault, with HI and LO temperature alarms and a normal dEF defrost indication. Many codes that appear after a power surge clear with a five minute power cycle; the rest point to a probe, a heater, or a relay that a technician replaces. We service Turbo Air reach ins, prep tables and merchandisers across Greater Boston, most the same day. Call (617) 778-2904.
Turbo Air reach in refrigerators, freezers, prep tables and merchandisers use a digital controller that displays the cabinet temperature and, when something fails, a short E code. The codes are similar across the M3, PRO, Super Deluxe and TSR lines. We read these off Turbo Air displays every week in Boston restaurant and market kitchens, so here is exactly what each code means, what your staff can check in minutes, and what needs a technician.
How the Turbo Air controller works
Turbo Air uses an electronic controller with one or more probes that runs the compressor, the evaporator fans and the defrost cycle, and shows the cabinet temperature on a display in the grille or the door frame. When a sensor reading is out of range or a cycle fails, the display alternates between the temperature and a code, and the controller usually keeps cooling in a fallback mode. So a code is a diagnostic flag, and the unit often keeps running while it shows it.
E1: cabinet air probe
E1 means the cabinet air probe is open, shorted or disconnected, so the controller cannot read the box temperature and runs the compressor on a timed fallback. Temperature control is lost until the probe is fixed. A technician checks the connector and measures the probe resistance, then replaces it. E1 is the main temperature sensor, and the box is running blind until it is repaired.
E2: evaporator or defrost probe
E2 means the evaporator probe has failed, the sensor on the coil that tells the controller when defrost is complete. The controller falls back to a timed defrost, which can leave ice on the coil or over defrost and warm the box. A technician replaces the probe. Left alone, E2 leads to icing.
E3: defrost fault
E3 means the defrost cycle did not complete as expected, because the evaporator did not warm to the termination temperature within the allowed time. That points to a failed defrost heater on freezers, a failed evaporator probe, a defrost relay fault, or heavy ice that the heater could not clear. A technician tests the heater and probe. E3 is a defrost system failure, and ice is likely.
E4: control or regulation fault
E4 indicates a temperature control failure: the box is not reaching or holding its setpoint within the controller limits. It can come from a thermostat or controller fault, a probe reading wrong, or, most often, a cooling problem the controller is reporting, such as a dirty condenser, a stopped fan, an iced evaporator, a leaking door gasket, or a low charge. Check the coil and fans first. E4 is often a cooling problem wearing a control code.
HI and LO: temperature alarms
HI means the cabinet is above the high alarm setpoint, from an open door, warm product just loaded, or a cooling failure. LO means it is below the low alarm, from a cold setpoint, a probe fault, or a stuck relay. For HI, check the door, the load, the condenser and the evaporator. For LO, check the setpoint and probe. The alarms are symptoms of a cooling or setpoint problem, not a part number by themselves.
Door alarm and dEF
Some Turbo Air models show a door open alarm when the door stays open past a delay or the door switch fails, and dEF or a defrost icon during defrost, which is normal. A defrost indication is not a fault. A door alarm with the door closed means the door switch.
Codes after a power surge
Turbo Air controllers can display a code after a power interruption or surge that has no underlying fault, and unplugging the unit for five minutes and restoring power clears it. A code that returns is real. A power cycle is the first step for any code. In older Boston buildings with shared panels and summer brownouts, this happens more than you would expect, so it is always worth the five minutes before you call.
The bottom line
Turbo Air error codes map to a few parts: E1 is a failed cabinet air probe, E2 a failed evaporator probe, E3 a defrost cycle that did not complete because of a heater, probe or relay fault, and E4 a temperature control failure that is often a cooling problem such as a dirty condenser or a stopped fan, while HI and LO are temperature alarms and dEF is a normal defrost indication. Unplug the unit for five minutes first, then check the door, the condenser coil, the evaporator for ice, and the fans, and have a technician replace a failed probe, heater or relay for a code that returns. If the box is simply warm with no code, start with our guide on a Turbo Air refrigerator not cooling.
Frequently asked
What does E1 mean on a Turbo Air refrigerator?
E1 means the controller has lost a valid reading from the cabinet air probe, the sensor that measures box temperature, because the probe failed, its wiring is damaged, or its connector is loose. Without that reading the controller runs the compressor on a fixed fallback cycle that keeps the box roughly cold but may drift, and the display shows E1. Unplug for five minutes to rule out a surge glitch. If E1 returns, a technician measures the probe resistance and replaces it, an inexpensive part. Monitor product temperature with a thermometer until the repair.
What does E3 mean on a Turbo Air freezer?
E3 is a defrost fault: the controller started a defrost cycle but the evaporator probe did not reach the termination temperature within the maximum defrost time, so it ended by timer and flagged the failure. On a freezer that usually means the electric defrost heater burned out, the evaporator probe failed, the defrost relay failed, or the coil is so heavily iced from a door leak that the heater could not clear it. Ice will build and the freezer will warm if it is not fixed. Unplug for five minutes; if E3 returns, a technician tests the heater for continuity, checks the probe, and inspects the coil.
What does E4 mean on a Turbo Air refrigerator?
E4 is a temperature control or regulation fault: the box is not reaching or holding its setpoint within the controller limits. It can be the controller or thermostat, a probe reading wrong, or, most often, a cooling problem the controller is reporting, a condenser clogged with grease, an iced evaporator, a stopped fan, a leaking door gasket, or a low charge. Unplug for five minutes, then clean the condenser, check the evaporator for ice, confirm the fans run, and test the door. If it cools normally after that, the code was reporting the cooling problem. If E4 persists with the cooling system healthy, a technician tests the probe and controller.
Why does my Turbo Air show a code after a power outage?
Turbo Air controllers are sensitive to power interruptions, and after an outage, a brownout or a lightning strike the controller can restart with a corrupted reading and display E1, E2, E4 or an alarm even though nothing failed. Switch the unit off, unplug it or turn off its breaker, wait about five minutes so the controller fully discharges, and restore power. If the code clears and the unit cools normally, it was a glitch. If the same code returns, the part it names has actually failed, possibly from the surge, and a technician should test it. A surge protector rated for the load, or whole building surge protection, reduces these events.
How do I reset a Turbo Air refrigerator controller?
Fix the cause of the code first, or the controller will show it again. Then turn the unit off, unplug it or switch off its breaker, wait five minutes, and restore power; the controller restarts and, if the fault is gone, shows the cabinet temperature. Many Turbo Air controllers also silence an alarm when you press and hold the set or alarm button for a few seconds, without cutting power. Do not enter the parameter programming menu without the Turbo Air service manual for your controller, since changing defrost intervals, probe offsets or setpoint limits can disable defrost or shift the box out of the safe range. If a code returns right after a reset, the part it names has failed and needs a technician.