Gree / Mace A8

Gree / Mace error code A8 indicates: Gree-Mace Versati II / Versati III / Versati IV Air-to-Water Thermodynamic Heat Pump: Diagnostic fault code A8 registered by the microcomputer controller. Hydronic heating primary water circuit pressure switch cut-out (< 0.5 bar).

The primary root cause for Gree / Mace code A8 is: On Gree-Mace appliances engineered with Gree Versati inverter hydronic module, Wilo PWM inverter water circulation pump, brazed plate heat exchanger, differential hydraulic flow switch (contact < 1 Ω), and 50 kΩ compressor discharge NTC sensor: hydronic heating circuit water pressure dropping below 0.5 bar Metrological tolerance verification: water pressure switch contacts closed (< 1.0 Ω) above 0.8 bar; trip at 0.5 bar..

To resolve error code A8: Disconnect mains power before servicing. Unplug the harness at the main PCB and use a calibrated digital multimeter: check system expansion vessel, repressurize circuit to 1.5 bar, and test switch continuity. Inspect contacts for pin oxidation or loose terminals. Replace defective part if out of tolerance, re-energize and clear error: On the wired master touch controller: tap Menu -> User Setup -> Troubleshooting -> Clear Fault Record, enter password '0000' or hold 'ON/OFF' + 'CONFIRM' for 5 seconds. Switch off mains power to both outdoor unit and indoor hydrobox for 60 seconds to reset communication and safety relays.

Resetting power (unplugging for 5–10 minutes) clears temporary memory errors. However, if Gree / Mace code A8 persists, the physical component causing On Gree-Mace appliances engineered with Gree Versati inverter hydronic module, Wilo PWM inverter water circulation pump, brazed plate heat exchanger, differential hydraulic flow switch (contact < 1 Ω), and 50 kΩ compressor discharge NTC sensor: hydronic heating circuit water pressure dropping below 0.5 bar Metrological tolerance verification: water pressure switch contacts closed (< 1.0 Ω) above 0.8 bar; trip at 0.5 bar. 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.