Aircon Blowing Warm Air? Common Causes & Step-by-Step Fixes

There’s nothing worse than turning on your air conditioner on a hot Singapore afternoon only to feel warm room-temperature air blowing out. When an aircon stops cooling, it indicates an issue in the refrigeration or electrical system.

Here are the top reasons and corresponding fixes:

1. Faulty Start/Run Capacitor

The capacitor acts as a battery boost to jumpstart the outdoor compressor motor. If the capacitor fails due to heat wear or age, the indoor fan will blow room air, but the outdoor unit won't produce cooling.

Fix: Quick replacement of the outdoor compressor capacitor.

2. Refrigerant Gas Leakage

Refrigerant travels in a sealed closed-loop copper circuit. If vibration or copper oxidation causes microscopic pinhole leaks, gas escapes over time. Without gas, heat exchange cannot happen.

Fix: Pressure-test copper pipes, seal leaking joints, and top up refrigerant gas to specifications.

3. Dirty Outdoor Condenser Unit

If the outdoor condenser unit is caked with thick street dust and grime, it cannot expel absorbed indoor heat. The compressor overheats and automatically shuts down to prevent motor burnout.

Fix: High-pressure water jet washing of the outdoor condenser coils.

4. Faulty Thermistor or Temperature Sensor

The thermistor reads room temperature and tells the main control PCB when to engage the compressor. A defective sensor misreads room temperature, causing the system to stay in idle fan mode.

Fix: Replacing the thermistor sensor wire array.

Summary

If your unit blows warm air, avoid running it continuously to prevent burning out the compressor motor. Call an experienced technician promptly for an accurate on-site diagnostic.