Gree Split AC Error Code H4 — What It Means & How to Fix It

What Does This Error Mean?

H4 means both the indoor and outdoor coils are in an overload protection state simultaneously. This is usually caused by severely restricted airflow on both units at the same time. Check the indoor air filter and outdoor unit clearance before calling a technician.

Affected Models

Gree FAIRY Series
Gree LOMO Series
Gree U-MATCH Series
Gree PULAR Series
Gree Inverter Split System

Common Causes

Severely clogged indoor air filter blocking airflow over the evaporator
Blocked outdoor unit with debris or obstructions restricting condenser airflow
Indoor fan not operating at the correct speed
Outdoor fan running slowly or not at all
Low refrigerant charge causing both coils to operate at abnormal temperatures

How to Fix It

Turn the AC off and let it rest for 20 minutes.

H4 triggers a protective shutdown. The system needs time to cool before it will allow a restart.
Remove and clean the indoor air filter — rinse with warm water if it is clogged with dust.

A heavily clogged filter starves the indoor coil of air, causing it to operate at extreme temperatures. This is the most common indoor-side cause.
Go to the outdoor unit and clear any debris, leaves, or obstructions around it. Check that there is at least 60 cm of clear space on all sides.

The outdoor unit must be checked at the same time as the indoor filter — H4 involves both sides of the system.
Rinse the outdoor condenser coil gently with a garden hose if it appears dirty.

Even partial blockage of the outdoor coil can push the outdoor coil into overload protection when combined with a restricted indoor filter.
Restart and monitor. If H4 returns after cleaning both units, call a technician to check refrigerant level and fan motor performance.

If both airflow paths are clear and H4 still occurs, the refrigerant charge or a fan motor is the likely cause.

When to Call a Professional

Call a technician if H4 persists after cleaning both the indoor filter and outdoor coil. Low refrigerant requires a licensed technician to diagnose and recharge. If both fans are not operating correctly, professional diagnosis of the PCBs and motors is needed.

Frequently Asked Questions

Why does H4 involve both indoor and outdoor coils at once?

H4 is triggered when the system detects abnormal temperatures at both coils simultaneously. This often happens when the entire refrigerant circuit is under stress — such as with low refrigerant or blocked airflow on both sides. Fixing only one side rarely resolves H4 permanently.

Can H4 appear if I close all the vents in unused rooms?

Yes — closing too many supply vents in a ducted system or blocking return air grilles starves the indoor unit of airflow. A split AC indoor unit needs unobstructed air return to work correctly. Never block or close more than one or two vents in a room served by a split AC.

How is H4 different from E1 or E2?

E1 is a high-pressure fault on the outdoor side only, and E2 is an anti-freeze protection on the indoor coil only. H4 is triggered when both sides of the system are in overload simultaneously. H4 is a broader system stress indicator than either E1 or E2 alone.