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Ice on Your Aircon? What Causes It and How to Fix It
Frost or ice on the copper pipes or indoor unit. Usually means blocked airflow or low gas -- sometimes both.
2-4 hours (defrosting) + fix
Difficulty: Easy to Medium Last updated: March 2026
What You Can Fix Yourself
Why Ice Forms on Your Aircon
Your aircon works by circulating cold refrigerant through the evaporator coil. Warm, humid air passes over this coil, gets cooled, and the moisture condenses as water (which drains away normally).
When something disrupts this process — restricted airflow, low refrigerant, or a faulty component — the coil gets too cold and the moisture freezes instead of draining. You'll see ice on the copper pipes, the evaporator coil, or even the indoor unit casing.
Step 1: Defrost the Unit
Before doing anything else, defrost your aircon:
1. Turn off cooling mode
2. Switch to **fan-only mode** and let it run for 2-4 hours
3. Place towels below the unit to catch melting ice
4. Do not scrape or chip ice off — you can damage the coils
Never run the aircon with ice on it — it reduces cooling, wastes energy, and can damage the compressor.
Step 2: Clean or Replace Filters
Blocked airflow from dirty filters is the #1 cause of ice formation. After defrosting:
1. Remove and clean the filters (wash under running water)
2. Let them dry completely
3. Reinstall and test the aircon on cooling mode
If the ice was caused by dirty filters, the problem should be resolved.
Check for Blocked Vents
Make sure nothing is blocking the indoor unit's air intake or output:
- No curtains draped over the unit
- No furniture pushed up against it
- Vents are fully open (not partially closed)
Restricted airflow = cold air can't move = coils freeze.
When to Call a Professional
Low Refrigerant
If filters are clean and airflow is unobstructed, low refrigerant is the likely cause. Low refrigerant reduces system pressure, causing the evaporator coil to drop below freezing temperature.
A technician will need to check for leaks, repair them, and top up the refrigerant. Cost: $60-$150 for the gas top-up, plus leak repair.
Faulty Components
Less common causes include:
- **Faulty blower fan** — not pushing enough air across the coil
- **Faulty expansion valve** — regulates refrigerant flow into the evaporator
- **Faulty thermostat** — doesn't signal the compressor to stop
All require professional diagnosis and repair.
When to Call a Pro
If ice returns after cleaning filters and ensuring good airflow, call a professional. Recurring ice formation usually means a refrigerant leak or faulty component that won't fix itself.
Browse contractor directory →Maintenance Tip
Ice formation is almost always preventable with regular filter cleaning (every 2-3 weeks) and quarterly servicing.