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AC Freezing Up
in Portland, ME
You notice ice on the copper lines going into your home, or maybe water pooling under the air handler. The evaporator coil inside the unit has frozen solid. This happens in Portland homes when airflow gets blocked or when refrigerant is low, and it can happen even on a 75-degree day. If the ice melts without the drain working right, you can end up with water damage to your ceiling or floor.
Quick Answer
Ice on your AC usually means restricted airflow or low refrigerant. Both problems cause the coil temperature to drop below freezing and ice over. In Portland, dirty filters are the most common cause, especially in homes that were closed up all winter. Turn the system off and call (207) 544-5500 to find out which problem you have before it floods your floor.
Telltale Signs
Warning Signs to Watch For
- Visible ice on the refrigerant lines near the indoor unit
- Water dripping or pooling on the floor below the air handler
- Very little or no airflow from the vents even though the system is running
- The outdoor unit runs but the house doesn't cool down
- A musty smell coming from the vents when the system runs
- Ice visible on the outdoor unit itself
Root Causes
What Causes AC Freezing Up?
Blocked Airflow From Dirty Filter
The evaporator coil needs warm air moving across it to stay above freezing. When the filter gets clogged, not enough air reaches the coil and it drops below 32 degrees. In Portland homes that are closed up from October through May, filters can get thick with dust and debris before anyone notices.
The Fix
Filter Replacement and Coil Thaw
Replace the filter and turn the system to fan-only mode to thaw the coil. Once thawed, check that airflow is fully restored before switching back to cooling.
Low Refrigerant From a Leak
When refrigerant is low, the pressure inside the coil drops too far and the coil gets much colder than it should. Ice builds up fast. Refrigerant leaks don't fix themselves, and systems in Portland homes built before 2000 often have older copper lines that develop small pinhole leaks over time.
The Fix
Leak Detection and Refrigerant Recharge
A tech finds and seals the leak, then recharges the system to the correct level. Running a low refrigerant system for a long time can damage the compressor.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Blocked Airflow From Dirty Filter | Low Refrigerant From a Leak |
|---|---|---|
| Ice on lines and filter is visibly clogged with dust | ||
| Ice on lines but filter was just replaced | ||
| Water on the floor below the indoor unit | ||
| No airflow from vents with system running | ||
| System freezes up repeatedly even with a clean filter |
Free Inspection
Get a Diagnosis in Portland
An on-site inspection is the only way to confirm which cause applies to your property. Free, no obligation.
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