Fujitsu Mini Split Error Code 94: Outdoor Unit Trip Detection, Compressor Overcurrent (Meaning, Causes, Fixes)

What the code means

Fujitsu's service manuals list E:94 as "Trip detection (Outdoor unit)", and Fujitsu's troubleshooting guide calls it an over current error. The outdoor main PCB stops the inverter compressor whenever it sees over-current after the compressor has finished its start-up; when that protection stop happens 10 times in a row, the unit locks out and shows 94. The count resets once the compressor starts up normally. On the indoor unit the code shows as the Operation light flashing 9 times, the Timer light flashing 4 times and the Economy light flashing continuously (detailed code 94.1 on units that show sub-codes). This is different from 95, which is a compressor motor control (rotor position) error, and 65, which is an IPM (power module) error.

Likely causes

• The outdoor unit can't get rid of heat: something blocking the air passages, clogged heat exchanger fins or the outdoor unit's own discharged air being sucked back in (Fujitsu's first check).
• An outdoor fan motor that isn't running properly.
• Very high ambient temperature around the outdoor unit, for example from another heat source nearby.
• A burnt, loose or poorly connected compressor harness or terminal (Fujitsu Australia's E:94 procedure).
• A failed main PCB, or the inverter PCB on models that have a separate one.
• A failed inverter compressor (locked rotor or shorted winding).

Safe DIY checks

1. Look at the outdoor unit. Clear away leaves, plants, snow, covers or anything else within a couple of feet that blocks air going in or out.
2. If the outdoor coil fins are visibly packed with dirt or debris, turn the power off and gently clean them with a coil cleaner or a garden hose on low pressure, spraying from the inside out where you can.
3. Make sure the hot air coming out of the outdoor unit isn't trapped by a wall, fence or enclosure and pulled straight back in, and that a dryer vent or other heat source isn't blowing on it.
4. Turn the mini split off at the breaker or disconnect, wait a few minutes, then turn it back on. If the unit then runs, watch whether the outdoor fan is turning while the compressor runs.
5. If 94 comes back, call a licensed HVAC technician and tell them the code, the indoor light pattern (9 flashes, 4 flashes, continuous) and the outdoor model number.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• 11 Fujitsu Mini Split 11
• 22 Fujitsu Mini Split 22
• 35 Fujitsu Mini Split 35
• 51 Fujitsu Mini Split 51
• 53 Fujitsu Mini Split 53

All Fujitsu codes →

Sources

1. Fujitsu AIRSTAGE wall-mounted service manual (AST series, via Beijer Ref) 2-21: E:94 Trip detection (Outdoor unit), Operation 9 / Timer 4 / Economy continuous; over-current stop after compressor start completed 10 times in a row, count reset on start-up; causes outdoor fan, heat exchanger, ambient, main PCB, compressor lock or winding short; check points fan/coil/ambient, main PCB, compressor
2. Fujitsu 2019 Troubleshooting Guide: 94 Over current error / Trip detection, 9-4-continuous flashes; clogged heat exchanger, condenser fan motor defective, discharged air not sucked in; 94.1 outdoor unit trip detection
3. Fujitsu ABYG36KRTA service manual 2-27 (ManualsLib p.72): E:94 Trip detection, check fan/heat exchanger/ambient, then replace inverter PCB, main PCB, compressor
4. Fujitsu General Australia, ARTG/AOTG ducted R410A units: E:94 trip detection / over current flow (airflow and coil, compressor harness, winding resistance U-V/V-W/U-W, IPM diode test before PCB)