The H3 error code shows up on Gree mini split air conditioners and many other brands. It means the overload protection for the compressor has tripped or is faulty.
If you have another brand check your units manual to verify H3 is a compressor overload protection which is common but some units have different definitions.
The problem is in your outdoor unit. Several things can cause it.
What Is an H3 Error Code?
The H3 code indicates that the compressor overload protection has shut down the outdoor unit. A thermostat sensor monitors the compressor temperature and cuts power if it reaches 115 degrees.
When the thermostat trips, the entire outdoor unit stops working within three seconds. The H3 code then displays on the indoor unit.
H3 Error Code Symptoms
- H3 displayed on indoor unit screen
- Outdoor unit stops running
- No cooling from the system
- Unit shuts down within three seconds of overheating
What Causes an H3 Error Code?
- Loose white wire connection at the compressor thermostat
- Faulty compressor thermostat
- Dirty or clogged outdoor condenser coil
- Clogged capillary tube or expansion valve
- Failed outdoor fan motor
- Faulty expansion valve that won’t open properly
- Refrigerant leak
How To Diagnose an H3 Error Code
Start with the outdoor unit. Look for obvious issues first.
Check the Thermostat Wire Connection
A white wire attaches to the compressor thermostat connector. If this wire is loose or not properly inserted into the connector, it can cause an H3 code.
Make sure the connection is secure.
Test the Compressor Thermostat
The thermostat is installed on top of the compressor terminals. Remove the nut to open the cover over the compressor terminals.
Pull the thermostat out of the compressor. It may have white or red wires depending on the model.
Set your multimeter to ohmmeter mode. The resistance value should be between 1 and 500 ohms.
It must be less than one kilo ohm. If the reading is one kilo ohm or higher, the thermostat is faulty and needs replacement.
The best resistance value is between 1 and 10 ohms. A reading around 0.03 ohms means the thermostat has almost no resistance and works like a wire.
The thermostat begins to work at 95 degrees. When compressor temperature reaches 100 to 115 degrees, it senses the temperature and the internal switch opens within three seconds.
The motherboard detects that continuity is broken and shuts down the unit.
Inspect the Outdoor Condenser Coil
A dirty or dusty condenser will cause the compressor to overheat. The thermostat will shut it down.
Clean the outdoor condenser coil if it’s clogged.
Check the Capillary Tube or Expansion Valve
Some models use a capillary tube protected in a charcoal sheet to prevent vibration. Others use an expansion valve.
If the capillary tube becomes clogged, the compressor will overheat. The thermostat will trip and the H3 error will display.
The expansion valve can also fail. When the expansion valve won’t open properly, the condenser overheats and transfers all the load to the compressor.
Test the Outdoor Fan Motor
If the outdoor fan becomes problematic or stops working, the heat exchanger will overheat. The compressor will take on more load and overheat.
This will trigger the H3 error.
Check for Refrigerant Leaks
When refrigerant leaks out, no cool refrigerant flows through the suction line. Normally the discharge line cools itself and the evaporator when cool refrigerant returns through the suction pipe.
The cooling from the refrigerant helps the compressor maintain normal temperatures. Without it, the compressor overheats and the H3 error displays.
How To Fix an H3 Error Code
Once you’ve found the cause, the fix is usually straightforward. Secure any loose wire connections at the compressor thermostat.
Replace a faulty thermostat with a new one. The resistance reading will tell you if replacement is needed.
Clean the outdoor condenser coil if it’s dirty. Use a coil cleaner and low-pressure water.
A clogged capillary tube or faulty expansion valve requires replacement. This is typically a job for a technician with refrigerant recovery equipment.
Replace a failed outdoor fan motor. Test the motor and capacitor if you suspect fan issues.
Refrigerant leaks need to be located, repaired, and the system recharged. This also requires professional equipment.
Can I Run the Unit with an H3 Error Code?
No. The unit shuts itself down when the H3 code displays.
The overload protection is there to prevent compressor damage from overheating. Running a unit with this fault will likely damage the compressor.
How Serious Is the H3 Error Code?
It’s serious because it indicates the compressor is overheating. The protection system is working to prevent permanent damage.
Address the underlying cause quickly. Continued overheating can destroy the compressor.
Is an H3 Error Code Expensive to Fix?
It depends on the cause. A loose wire costs nothing.
A replacement compressor thermostat is usually inexpensive. Cleaning the condenser coil is a DIY job with minimal cost.
Refrigerant leaks, expansion valve replacement, and compressor work require a technician. Shop diagnostic fees typically start around $100, and repair costs vary based on the specific problem.
Summary
The H3 error code on Gree and other mini split brands indicates compressor overload protection has tripped. The thermostat on the compressor shuts down the outdoor unit when temperature reaches 115 degrees.
Start diagnosis by checking the white wire connection at the compressor thermostat. Test the thermostat with a multimeter set to ohms.
The reading should be between 1 and 500 ohms, ideally between 1 and 10 ohms. Readings above one kilo ohm mean the thermostat is faulty.
Other causes include a dirty condenser coil, clogged capillary tube, failed expansion valve, broken outdoor fan motor, or refrigerant leak. Each of these conditions causes the compressor to overheat.
Fix the problem based on what you find. Simple fixes like securing wires or cleaning coils are DIY jobs.
Refrigerant work and expansion valve replacement typically require a technician. Address the H3 code quickly to prevent compressor damage.
Have you had an issue with an H3 error code on your mini split? Let us know your fix or problem below.