Gree Error Code on: Valve test running / unit started (Heat Pump)

Updated October 15, 2026 · by Aurora Star Tech Inc.

Gree error code on on a heat pump means: Valve test running / unit started. It is also called Gree diagnostic code on.

Low severityHeat PumpGree GMV6 Mini VRF

Homeowner? What Gree code on means for you

Usually minor Your heat pump is reporting: Valve test running / unit started. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Gree error code on mean?

10/on shows while the system inspects the outdoor valves at commissioning step 10; the compressor runs for about 2 minutes and then stops. A plain on is also what the outdoor board shows after commissioning once the unit is started.

Applies to: Gree GMV6 Ultra Heat Mini VRF 36-60k (GMV-V..WL/C-T(U))

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Gree models that use code on

GMV-V36WL/C-T(U)GMV-V48WL/C-T(U)GMV-V60WL/C-T(U)

Other Gree Heat Pump codes

Code	Meaning
nJ	High temperature prevention when heating (factory function)
nn	Connection pipe length modification (factory function)
nU	Cancel indoor long-distance shielding (factory function)
oC	Commissioning step passed (OK)
oE	Undefined outdoor unit error
oF	Debugging finished / standby
Operation lamp	Operation lamp lit (power on / standby)
Outdoor comm light blinking	Outdoor communication light blinking (normal)
P0	Compressor minimum-frequency test display
P1	Compressor rated (nominal)-frequency test display
P2	Compressor maximum-frequency test display
P3	Compressor intermediate-frequency test display

All Gree Heat Pump error codes →

Gree code on: homeowner questions

What does Gree code on mean?

Valve test running / unit started. 10/on shows while the system inspects the outdoor valves at commissioning step 10; the compressor runs for about 2 minutes and then stops. A plain on is also what the outdoor board shows after commissioning once the unit is started.

Is it safe to keep using my heat pump with code on?

Usually yes. Code on is normally minor, but if it keeps coming back have it checked.

Can I reset Gree code on myself?

You can try one reset (power off for 30 seconds, then on). If Gree code on comes back, the cause is still there and a licensed technician should check it.

Who can fix Gree code on near me?

Aurora Star Tech Inc. repairs Gree heat pumps in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air

Troubleshooting guides

Cap the maximum output (function n4) Gree · Heat Pump
Compressor will not run - Gree ductless Gree · Heat Pump
Force a defrost cycle from the remote Gree · Heat Pump
Force a defrost from the outdoor board (function n3) Gree · Heat Pump
Limit the whole system to heating, cooling or fan only (function A6) Gree · Heat Pump
Louver will not swing - Gree ductless Gree · Heat Pump
Noise or vibration - Gree ductless Gree · Heat Pump
Offset indoor engineering numbers (function n5) Gree · Heat Pump
Outdoor fan will not run - Gree ductless Gree · Heat Pump
Read live running parameters of an outdoor module (function n7) Gree · Heat Pump
Read or clear the fault history (function n6) Gree · Heat Pump
Restore system defaults from the outdoor board (0C) Gree · Heat Pump
Run the outdoor commissioning sequence (steps 01 to 17) Gree · Heat Pump
Set automatic energy saving (function n0) Gree · Heat Pump
Set outdoor silence mode (function A7) Gree · Heat Pump
Show indoor engineering numbers on the indoor units (function n8) Gree · Heat Pump
Start pump-down (refrigerant recycle) mode, function A2 Gree · Heat Pump
Start vacuum mode for evacuating pipework (function A8) Gree · Heat Pump
Unit will not start - Gree ductless Gree · Heat Pump
View the stored malfunction code on the remote (LIGHT x6) Gree · Heat Pump
Water leaking from indoor unit - Gree ductless Gree · Heat Pump
Weak cooling or heating - Gree ductless Gree · Heat Pump

Source: Gree GMV6 Ultra Heat Mini VRF 36-60k (GMV-V36-48-60WL-C-T(U)) service.pdf - section 3.2.2.2 Test Operation and Debugging; 3.2.4. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.