Princess P4

Princess error code P4 indicates: Princess Smart Mobile Air Conditioner & Digital Dehumidifier Series: Diagnostic fault code P4 registered by the microcomputer controller. Refrigeration system cooling loss; compressor runs without condensation production.

The primary root cause for Princess code P4 is: On Princess appliances engineered with R290 hermetic rotary compressor, aluminum fin evaporator and condenser coils, capacitive humidity sensor, and float-operated water switch: refrigerant gas leak (R290 propane charge lost) from cracked copper braze joint Metrological tolerance verification: evaporator NTC and ambient NTC temperature difference < 3.0°C after 20 min compressor run..

To resolve error code P4: Disconnect mains power before servicing. Unplug the harness at the main PCB and use a calibrated digital multimeter: inspect refrigeration lines for oily residue; check refrigerant pressures with manifold gauges. Inspect contacts for pin oxidation or loose terminals. Replace defective part if out of tolerance, re-energize and clear error: unplug from wall socket for 5 minutes, empty the water collection tank, reinsert until the float clicks, and hold Power for 4 seconds.

Resetting power (unplugging for 5–10 minutes) clears temporary memory errors. However, if Princess code P4 persists, the physical component causing On Princess appliances engineered with R290 hermetic rotary compressor, aluminum fin evaporator and condenser coils, capacitive humidity sensor, and float-operated water switch: refrigerant gas leak (R290 propane charge lost) from cracked copper braze joint Metrological tolerance verification: evaporator NTC and ambient NTC temperature difference < 3.0°C after 20 min compressor run. must be inspected or replaced.

Set a digital multimeter to ohms (Ω). Disconnect power and test Compressor Motor Windings (Run/Start) & Defrost Heater across Across 3 compressor pins (Common, Run, Start): R(C-S) + R(C-R) = R(S-R). Winding to earth: >20MΩ (OL).. Expected nominal reading is 15Ω–25Ω (Run C-R), 20Ω–35Ω (Start C-S), 200Ω–400Ω (Defrost Heater). PTC Relay: 10Ω–30Ω at 25°C.. Tolerance: ±10%. Any low insulation resistance to casing (<2MΩ) trips the breaker. Defrost bimetal reads <0.5Ω when sub-zero..

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.