Hisense mini split error code 18

DC compressor start failure.

TypeProtection
SystemCompressor / inverter
Can I fix it?Technician job

What 18 means on a Hisense

The drive tried to start the compressor and could not get it turning.

On this platform, 18 is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.

Common causes

A failed outdoor drive board.
A seized or failed compressor.
Loose compressor terminals.
Low supply voltage.

How to fix it yourself

Do the reset and the visual checks, but the underlying repair needs a technician with a meter and the service manual.

Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
If you own a multimeter and are comfortable using it, measure the supply voltage at the outdoor unit's L1 and L2 terminals with the unit running. A 230 V system should read roughly 208 to 253 VAC.
Do not keep retrying after two failed starts.

Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.

When to call a technician

Technician diagnosis of the drive and compressor.

Which Hisense units show 18

This page applies to Hisense Hisense inverter single-zone and Hisense multi-zone units. Hisense's own documentation lists 18 as "DC compressor start failure", the same definition used across the Hisense it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.

Where Hisense shows this code

Hisense inverter splits store the fault as a number. When the compressor has stopped on a fault, point the remote at the unit and press the SLEEP button 10 times within 10 seconds: the indoor display then shows the code (a second stored fault shows after four more presses). The Sleep, Timer and Running lamps also blink a pattern that matches the code. Newer models show the number on the display without the button sequence. Codes 1 to 21 are outdoor-unit faults and protections; 33 to 41 are indoor-unit faults. 0 means no fault is stored.

Other Hisense codes

Same part of the system as 18:

5IPM module protection 13Compressor discharge temperature too high 15Compressor shell temperature too high 19Compressor drive fault

0No fault stored (normal)1Outdoor coil temperature sensor fault (open or short circuit)2Compressor discharge (exhaust) temperature sensor fault (open or short circuit)6AC supply voltage too high or too low 7Communication error between indoor and outdoor units 10Communication error between outdoor unit and compressor driver board 11Outdoor unit EEPROM fault 14Outdoor ambient temperature sensor fault (open or short circuit)

All Hisense error codes

18 on other brands

The same characters do not always mean the same thing. Check the brand on your unit.

Haier 18 Compressor out of synchronism

Questions people ask

Can I reset a Hisense 18 code myself?

Yes. Turn the system off at the breaker for five minutes, then restart it. If 18 comes back, the fault is real and needs the checks above.

Is it safe to keep running a Hisense showing 18?

Not repeatedly. A protection code means the unit stopped itself to prevent damage, and resetting it over and over can turn a cheap repair into a compressor failure. Reset once, check the basics, and stop if it returns.

What will a technician check for 18?

Technician diagnosis of the drive and compressor. Ask for the measurements, not just a parts quote.

Sources

Hisense split-type air conditioner service manual, section 7-1 Error Code Table (North America inverter models)

Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.