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AC Freezing Up
in Spokane, WA
Ice forming on your AC looks strange in summer but it happens a lot in Spokane. When the evaporator coil gets too cold, moisture in the air freezes on it. The two most common reasons are a dirty air filter blocking airflow and low refrigerant. If you keep running a frozen system, you can burn out the compressor.
Quick Answer
Ice on an AC unit means airflow is blocked or refrigerant is low. Both problems make the coil get too cold and freeze. In Spokane, dusty conditions from dry summers and wildfire smoke clog filters faster than homeowners expect. Turn the unit off, let it thaw, and call (509) 472-2017 to find out which problem caused it.
Telltale Signs
Warning Signs to Watch For
- Visible ice on the refrigerant lines going into the house or on the outdoor unit
- Airflow from vents drops off noticeably over several hours
- The AC runs constantly but the house gets warmer instead of cooler
- Water drips or puddles near the indoor air handler as ice thaws
- The outdoor unit is running but you can see frost on the copper lines
Root Causes
What Causes AC Freezing Up?
Clogged Air Filter
A dirty filter slows the air moving across the evaporator coil. Without enough warm air flowing over it, the coil drops below freezing and ice forms. Spokane summers bring wildfire smoke and dust that can clog a standard filter in just a few weeks instead of the usual month.
The Fix
Filter Replacement and Airflow Check
Replace the filter and let the system thaw completely before restarting. If it freezes again with a clean filter, the problem is somewhere else in the airflow path.
Low Refrigerant
When refrigerant is low, the pressure inside the coil drops and the coil gets much colder than it should. Ice builds up fast. A slow refrigerant leak can go unnoticed for months until the system starts freezing on warm afternoons.
The Fix
Leak Detection and Refrigerant Recharge
A tech finds and fixes the leak, then recharges the system. Running it low will freeze the coil every time, so the leak has to be fixed, not just topped off.
Blocked or Closed Vents
Closing too many supply vents in rooms you're not using cuts airflow through the whole system. The coil doesn't get enough warm air and starts to freeze. This is especially common in two-story Spokane homes where people close downstairs vents to try to push more air upstairs.
The Fix
Vent and Ductwork Inspection
Open all supply vents and have a tech check duct runs for blockages or collapsed sections. A balanced system moves air evenly and won't freeze.
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 | Clogged Air Filter | Low Refrigerant | Blocked or Closed Vents |
|---|---|---|---|
| Filter is gray and matted when you pull it out | |||
| Ice forms even with a recently changed filter | |||
| Several vents in the house are closed or blocked by furniture | |||
| System froze up during a stretch of heavy wildfire smoke | |||
| Refrigerant lines outside are frosted all the way to the outdoor unit | |||
| Airflow feels strong in some rooms and almost nothing in others |
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