Mini-split error codes and blinking lights: what to do first

Do this first

These steps work on any brand.

Write it down. Take a photo of the display, or count the blinks: which light, how many times, and how long it pauses. Find the model number on the label on the side of the indoor unit. Carrier says to record the code so a technician can use it (Carrier), and Senville asks for the code and model number when you contact support.
Check whether it’s a normal one. Defrost, filter reminders, and mode conflicts aren’t faults. See the next section.
Clean the filters, with the power off at the breaker. Daikin says that if the unit stops and its light flashes, clean the filters and restart it (Daikin). The filters guide has the steps.
Clear the air paths. Daikin says to remove anything blocking the air going into or out of the indoor or outdoor unit. LG adds clutter around the outdoor unit to its list for overheating codes.
Reset it once. Turn the unit off with the remote, then turn off its breaker, wait, and turn it back on. Brands give different waits: LG says 5 minutes, MRCOOL at least 15 (MRCOOL), and Carrier and Daikin about 20. Daikin says to use the air conditioner’s own breaker, not the main breaker for the house.
If the code comes back, call. LG says a code that returns after a reset needs a technician (LG). Daikin says a light that starts flashing again likely means a malfunction.

Codes that aren’t faults

Defrost. In heat mode on cold, damp days, frost builds on the outdoor unit and the system pauses to melt it. Senville shows dF, Gree shows H1, and on Fujitsu units the green operation light blinks slowly (Senville, Gree, Fujitsu). Fujitsu says it can take up to 15 minutes. The outdoor unit may steam and drip water while it does it. Wait it out.
Filter reminders. Senville’s CL means clean the filters. On some Fujitsu units, the green economy light flashes three times when the filters are due.
Mode conflicts. On a system with several indoor units, they can’t heat and cool at the same time. Gree shows E7, LG shows CH07, MRCOOL and Senville show dashes, and Fujitsu blinks the operation light. Put every indoor unit in the same mode.

The same code can mean different things

There’s no standard list. On Gree units, E2 is freeze protection. On older MRCOOL indoor units, E2 is a power-signal error, and on their multi-zone outdoor units it’s a communication fault (MRCOOL). On Senville, CL is a filter reminder; on Gree, CL shows while the unit runs its auto-clean cycle. MRCOOL lists its codes by generation and Senville by product series, so look yours up by brand and model, not by a code list from another brand. If you bought a Senville or MRCOOL unit online, its help center is the place to start.

What the codes are about

Every brand’s list sorts into the same few kinds. A few examples from the brands’ own pages:

Kind of code	Examples	What you can do
Airflow and coil temperature	Gree E2 (freeze protection); Senville PH 90/91 (coil temperature protection)	Clean the filters, clear blockages, reset once
Fans	LG CH10 (indoor fan)	Clear any visible debris, reset once; call if it comes back
Drain and water	LG CH04; Gree E9	See leaking water, then call
Communication and power	LG CH05; Senville EL 01	Reset once; call if it comes back
Sensors and circuit boards	MRCOOL indoor E4; Senville EH 60	Call
Refrigerant and pressure	LG CH38 (low refrigerant); Senville EL 0C (system lacks refrigerant)	Reset once; call if it comes back. See below
Compressor and outdoor unit	LG CH61 (outdoor unit overheating); Senville PC 0A (condenser high temperature)	Clear around the outdoor unit; call if it comes back

A refrigerant code that comes back after one reset needs a technician. Don’t add refrigerant yourself: EPA requires Section 608 certification to add refrigerant or connect hoses to the system (EPA). Not cooling or icing up explains why.

Blinking lights with no display

Many wall units have no screen and show trouble with blinking lights instead.

Mitsubishi: green lights may blink on the indoor unit. Trane, which sells Mitsubishi systems, says to check the owner’s manual and, in most cases, call for service (Trane).
Fujitsu: a slow blink of the green operation light in heat mode is defrost. If the operation and timer lights blink while the economy light blinks fast, Fujitsu says to stop the unit, turn off the breaker, and call (Fujitsu).
Daikin: a flashing operation light means turn the unit off, turn its breaker off for 20 minutes, and turn it back on. If it flashes again, contact your installer or Daikin (Daikin).
LG: some models show the code as a pattern of red blinks on the operation light, and LG says to call for service (LG).

Resetting it again and again isn’t a fix

Many codes are protection. The unit shuts itself down to keep a part from being damaged. LG says its low-refrigerant code is there to protect the unit from damage, and its overheating code is there to prevent damage or fire (LG). A reset clears the code, not the cause. If the breaker itself won’t stay on, LG says not to keep resetting it. See AC breaker keeps tripping.

Can a cleaning fix a code?

Sometimes. Codes about airflow and coil temperature can come from dirt. Gree’s freeze-protection code says to check the filters, and Senville’s coil temperature codes say to make sure airflow isn’t blocked and to clean the filters. The filters don’t fully protect the coil and wheel, as the cleaning guide explains, so clean filters don’t mean a clean unit. Shine a flashlight up through the louvers at the blower wheel.

A cleaning won’t fix a failed sensor, circuit board, fan motor, or compressor, or a refrigerant leak. And a home wash that gets water on the control board can cause new trouble. See cleaning bags and kits before you try one.

After a power outage

LG says a code can be temporary, caused by unstable power, and it lists one code that can show up after an outage or electrical work (LG). Once the power is steady, one reset is reasonable. If floodwater reached the outdoor unit or it was damaged, don’t reset it; leave it off and call. For the rest of a restart after a storm, see restarting AC after an outage.

Find your brand’s code list

Each brand publishes its own list. These are the official pages. If yours isn’t here, the owner’s manual has it.

Brand	Official code page	What you'll find
Mitsubishi	Trane: Mitsubishi remote and error codes Checked Oct 19, 2026	Mitsubishi's US site has no public code list. Trane, which sells Mitsubishi systems, says to check your owner's manual and, in most cases, call for service.
Daikin	Daikin Error Code Search Checked Oct 19, 2026	Enter the code to see what it means and the unit's status. This is Daikin's global site.
Fujitsu	Fujitsu AIRSTAGE troubleshooting Checked Oct 19, 2026	Explains normal blinks, such as defrost, and the checks to make first. Code meanings are in your model's manual.
LG	LG guide to error codes Checked Oct 19, 2026	What each common CH code means and what to try, starting with a 5-minute breaker reset.
Carrier	Carrier mini-split repair guide Checked Oct 19, 2026	No code list. Carrier says to write the code down for your technician and gives a 20-minute reset.
Gree	Gree homeowner quick guide Checked Oct 19, 2026	A short list of common codes, which ones are normal, and which ones need a technician.
Senville	Senville LETO error codes Checked Oct 19, 2026	Indoor, outdoor, and protection codes for the LETO series, plus the normal display codes like dF and CL.
MRCOOL	MRCOOL error codes Checked Oct 19, 2026	Indoor and outdoor codes for each product generation. Find your generation on the unit's label first.