Daikin Error Code E5: Compressor Overload or Compressor Motor Lock (Meaning, Causes, Fixes)
What the code means
Daikin's Entra wall mount service manual (FTK(X)B and RK(X)B AXVJU) lists E5 as "Compressor overload" in its inverter error code table, right before E6 (compressor lock or start-up abnormality) and E7 (outdoor fan motor lock). The overload signal comes from the discharge pipe thermistor and the OL (overload) protector circuit wired to connector S40 on the outdoor board, so E5 means the compressor got hotter than it should, usually because refrigerant isn't flowing the way it should. On Daikin's light commercial and VRV systems the same letters mean something a little different: the SkyAir inverter service manual SiUS25-501 defines E5 as "Outdoor unit: compressor motor lock," detected when the inverter board sees the compressor's position signal change pattern because the motor isn't turning, and Daikin's Simple Self-Diagnosis code list describes E5 as inverter compressor motor lock or overheat. Either way, the unit stops the compressor to protect it.
Likely causes
- A refrigerant shortage or leak, the first root cause Daikin lists for E5 on wall-mount units. Low charge makes the compressor run hot.
- A refrigerant stop valve on the outdoor unit that was left closed or isn't working, especially right after installation. SkyAir manuals list a closed stop valve as a cause of E5 compressor lock too.
- A discharge pipe thermistor that has come out of its holder, is disconnected, or has failed and reads wrong.
- A loose connector S40 or a disconnected overload (OL) protector lead on the outdoor board.
- A defective electronic expansion valve (EEV) or its coil, or a four way valve that isn't shifting properly.
- Water mixed into the refrigerant, or a clogged refrigerant line.
- A defective outdoor unit PCB.
- On SkyAir and VRV units (compressor motor lock): a locked compressor, high differential pressure at start-up (Daikin gives 73 psi or more), incorrect U, V, W wiring between the inverter and compressor, or a faulty inverter board. Daikin's VRV code list also names refrigerant overcharge and weak power supply capacity.
Safe DIY checks
Turn off the power before touching any connector; Daikin cautions that connecting or disconnecting connectors with power on can damage parts. The outdoor inverter board can hold a dangerous charge after power is removed. Refrigerant work, including leak repair, recovery and recharging, must be done by a certified technician (in the US, EPA Section 608 certification is required to handle refrigerant).
- Turn the system off, switch off the breaker for the outdoor unit, wait a few minutes, then restore power and try again. This clears a one-time trip.
- Clear leaves, snow, covers or stored items from around the outdoor unit and clean or replace the indoor filters so the system isn't working against poor airflow.
- If E5 showed up right after a new install or a move, call the installer. A stop valve left closed, a refrigerant leak at a flare, or wiring mixed up during installation is a common cause and is their fix.
- Note whether E5 appears in cooling, heating, or both, and how long the unit runs first. That helps a technician narrow down whether it's refrigerant, a valve, or a sensor.
- If E5 comes back after a reset, stop running the unit and call a licensed HVAC technician. Repeated overload or lock trips can damage the compressor, and the checks involve refrigerant and high voltage.
🛠 When to call a pro
- On wall-mount units, Daikin's E5 flowchart starts with the discharge pipe thermistor: reinsert it if it has come out of position, check its resistance against the thermistor table, and replace it if it's out of range.
- Checking that connectors are properly seated, then disconnecting connector S40 from the outdoor board and checking the resistance across the two OL terminals.
- Checking the electronic expansion valve and its coil and replacing the valve or coil if it has malfunctioned, then checking the four way valve and replacing the valve or coil if needed.
- Checking the refrigerant line using Daikin's refrigerant line check procedure, including the charge and for leaks, and replacing the outdoor PCB if everything else checks out.
- On some models Daikin's alternate flowchart has the technician disconnect the U, V, W compressor harness and check the compressor winding resistance, replacing the compressor if it is out of spec, and replacing the outdoor PCB if the compressor stops with no other fault.
- On SkyAir units (motor lock): confirming the stop valve is open, the U, V, W wiring is correct, and there's no high differential pressure at start-up; checking the compressor for a short or ground fault; and checking that the inverter output voltage is the same on all three phases. Unequal phases mean replacing the inverter board, and Daikin says to replace the compressor if the phases are equal and pressures don't change at all when it restarts.
Parts that commonly fix it
Always match the part number to your exact model.
Refrigerant leak detector
Used by a technician to find a leak before the system is repaired and recharged, since low refrigerant is Daikin's first listed cause.
Search eBay →Discharge pipe thermistor
Only if it fails Daikin's resistance check; match the exact Daikin outdoor unit model and part number.
Search eBay →Digital multimeter
Used with the power off to check thermistor, overload terminal and compressor winding resistance.
Search eBay →Sources
- Daikin Entra wall mount service manual FTK(X)B/RK(X)B AXVJU, 3.3 inverter error code table (E5 compressor overload) and E5 troubleshooting flowcharts (pp. 40-41), Daikin Comfort
- Daikin SkyAir Inverter service manual SiUS25-501, 4.16 "E5" Outdoor Unit: Compressor Motor Lock (detection, supposed causes, flowchart), Daikin Comfort
- Daikin Industries, Simple Self-Diagnosis by Malfunction Code (E5 inverter compressor motor lock or overheat)
Last reviewed 2026-10-24. Always confirm against the manual for your exact model number.