# Troubleshooting These guides work through a problem in the order worth checking, from the cheapest and most likely cause to the least. They are written to solve the issue, not to sell a replacement. _Last updated: 2026-09-28_ ## Articles - [Air Purifier Making a Rattling Noise: Causes and Fixes](https://www.smartairguide.com/troubleshooting/air-purifier-making-a-rattling-noise/) — Fix a rattling or buzzing air purifier: check the filter seating, shipping foam, debris, surface and screws before suspecting the fan bearing. - [Air Purifier Not Connecting to Wi-Fi: What to Check](https://www.smartairguide.com/troubleshooting/air-purifier-not-connecting-to-wifi/) — Work through the real causes of air purifier Wi-Fi pairing failures in order: 2.4 GHz band, router security, MAC filtering, range and app state. - [Dehumidifier Not Collecting Water: Causes and Fixes](https://www.smartairguide.com/troubleshooting/dehumidifier-not-collecting-water/) — A dehumidifier that runs but collects no water is usually at its setpoint, defrosting, or starved of airflow. Here is how to check each cause in order. - [Portable AC Blowing Warm Air: Troubleshooting Steps](https://www.smartairguide.com/troubleshooting/portable-ac-blowing-warm-air/) — Why a portable air conditioner blows warm air: mode, compressor delay, unsealed exhaust, hose problems and undersized BTU. Check these in order. - [Smart Fan Not Responding to the App: What to Check](https://www.smartairguide.com/troubleshooting/smart-fan-not-responding-to-the-app/) — A smart fan that ignores the app is usually offline on Wi-Fi. Check power, band, router isolation and firmware before re-adding the device. ## What you will find here - Appliance not connecting to Wi-Fi or the app - Dehumidifier not collecting water - Portable AC blowing warm air - Air purifier making a rattling noise ## Frequently asked questions **Q: When should I contact the manufacturer instead?** A: If the unit shows no power, smells like burning, leaks from the housing, or the checks do not change anything, stop and contact the manufacturer or a qualified technician. Do not open a sealed unit yourself. --- Canonical: