Gree / Mace P4

Gree / Mace error code P4 indicates: Gree-Mace G10 Inverter / Free Match / GMV5 / GMV6 Multi-VRF Commercial & Residential HVAC: Diagnostic fault code P4 registered by the microcomputer controller. Three-phase electrical power supply line sequence reversal or missing phase.

The primary root cause for Gree / Mace code P4 is: On Gree-Mace appliances engineered with Gree G10 Inverter low-frequency torque control, intelligent dual-stage rotary compressor, 46 Ω electronic expansion valve stepping motor coils, high-voltage PFC boost circuit (380V DC), and precision NTC thermistors (15 kΩ ambient, 20 kΩ coil, 50 kΩ discharge): three-phase supply line sequence inverted (counter-clockwise) or open phase fuse Metrological tolerance verification: 3-phase supply 400V AC ± 10%, clockwise phase sequence U -> V -> W..

To resolve error code P4: Disconnect mains power before servicing. Unplug the harness at the main PCB and use a calibrated digital multimeter: test phase sequence with rotation meter and swap two incoming supply leads at main isolator. Inspect contacts for pin oxidation or loose terminals. Replace defective part if out of tolerance, re-energize and clear error: Using the remote controller: point at the unit and press 'LIGHT' 6 times in 3 seconds (or hold 'TURBO' + 'MODE' for 5 seconds) to enter diagnostic query mode. For inverter lockout errors (H5, HC, P0, P8, E6), switch off the external electrical isolator / circuit breaker for at least 3 minutes to allow DC bus capacitors to fully discharge.

Resetting power (unplugging for 5–10 minutes) clears temporary memory errors. However, if Gree / Mace code P4 persists, the physical component causing On Gree-Mace appliances engineered with Gree G10 Inverter low-frequency torque control, intelligent dual-stage rotary compressor, 46 Ω electronic expansion valve stepping motor coils, high-voltage PFC boost circuit (380V DC), and precision NTC thermistors (15 kΩ ambient, 20 kΩ coil, 50 kΩ discharge): three-phase supply line sequence inverted (counter-clockwise) or open phase fuse Metrological tolerance verification: 3-phase supply 400V AC ± 10%, clockwise phase sequence U -> V -> W. must be inspected or replaced.

Set a digital multimeter to ohms (Ω). Disconnect power and test NTC Temperature Sensor Probe (Thermistor) across Across sensor pins 1-2 (unplugged harness). Expected nominal reading is 4.8kΩ–12kΩ (at 20°C–25°C). Tolerance: Negative temperature coefficient: resistance drops smoothly when warmed with fingers. OL = open circuit..

Standard electrical safety protocol: 1. Disconnect 230V mains power before opening panels. 2. Verify zero voltage at test points. 3. Allow hot water or heating elements to cool below 30°C before handling.