An air conditioner failing in Bangkok during summer (35°C+) is a household nightmare, and it almost always results from problems that accumulated gradually before the breakdown. IoT Predictive Maintenance detects warning signs 2–4 weeks in advance.
Vibration Sensor: Compressor Health Monitoring
SW-420 vibration sensor or ADXL345 3-axis accelerometer mounted on the outdoor compressor unit, connected to ESP32 with ESPHome firmware, sends data to Home Assistant via MQTT.
Normal vibration for a 1.5-ton Inverter compressor: 1–5 mm/s RMS. Values above 8 mm/s indicate compressor wear or imbalance. Values above 15 mm/s indicate serious damage requiring immediate service.
Power Consumption Anomaly Detection
A watt-measuring smart plug (Shelly 1PM or Tasmota-flashed Sonoff Pow R2) at the AC circuit breaker monitors consumption. A 1.5-ton Inverter at full load normally draws 800–1,200W. Sustained consumption above 1,400W may indicate: clogged filter (increased compressor load), refrigerant leak (compressor working harder), or dirty condenser fins.
Home Assistant uses anomaly detection (Holt-Winters forecasting or Z-Score) to flag power consumption deviating more than 20% from seasonal baseline → Yellow alert.
Filter Dirtiness Sensing
A differential pressure sensor (Honeywell ABPDRRT, THB 300–800) measures air pressure before and after the AC filter. Rising pressure differential indicates filter clogging. When pressure drop exceeds baseline by 30% → LINE notification to change filter.
Budget alternative: a Wi-Fi camera (Wyze Cam, Reolink) photographs the filter every 2 weeks. HA Image Processing with brightness analysis checks filter colour (white = clean, grey/black = replace).
Refrigerant Leak Detection
A refrigerant leak sensor (R32/R410A compatible, such as Figaro TGS2611-E00) near the indoor unit monitors for Freon leaks. On detection of R32/R410A above 500 ppm → LINE alert, automatic AC shutdown via smart plug, and ventilation fan activation.
Maintenance Dashboard in Home Assistant
Dashboard displays: last filter change date, compressor runtime hours (typical compressor life 50,000–80,000 hours), 30-day average power consumption versus today, vibration level, and upcoming maintenance prediction.
Automation: monthly LINE summary report to homeowner with maintenance recommendations and estimated costs.
Predictive Maintenance ROI
Total sensor system cost: THB 2,000–5,000. Emergency compressor repair: THB 5,000–15,000. Preventing one emergency failure recovers the entire hardware investment immediately. Clean filters and fins also reduce electricity consumption 10–15% year-round.