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AC Unit Freezing Up
in Plano, TX
When ice forms on your AC, it looks like the system is working hard, but it's actually failing. Plano's humid summers, often sitting above 60 percent humidity from June through August, make the problem worse because there's more moisture in the air to freeze on the coil. Running a frozen unit can damage the compressor, which is an expensive part to replace.
Quick Answer
A frozen AC usually means airflow is blocked or refrigerant is low. In Plano's high humidity summers, ice builds fast once airflow drops below what the coil needs. Turn the system to fan-only to let it thaw, then call (469) 960-3779 to find the real cause before you run it again.
Telltale Signs
Warning Signs to Watch For
- Visible ice on the copper refrigerant lines near the indoor unit or outside
- Little or no air coming from the vents even though the system is running
- Water dripping or pooling around the indoor air handler
- The outdoor unit runs but the house won't cool down
- A musty or wet smell coming from the vents
Root Causes
What Causes AC Unit Freezing Up?
Restricted Airflow from a Dirty Filter
The evaporator coil needs a steady flow of warm air to stay above freezing. When a clogged filter cuts that airflow, the coil gets too cold and moisture in the air freezes on contact. Plano homes with pets or with the system running nearly non-stop through a 100-degree July can clog a standard filter in three to four weeks instead of the usual 90 days.
The Fix
Filter Replacement and Airflow Inspection
Replace the filter, let the coil thaw completely with the fan on, and then check every vent and return for blockages. A technician will also look at duct condition to make sure airflow meets the system's requirements.
Low Refrigerant Pressure
When refrigerant is low due to a leak, the pressure inside the evaporator coil drops too far and the coil temperature falls below freezing. Humidity in the Plano air then freezes on the coil surface faster than it can drain away. The ice keeps building until airflow is completely blocked.
The Fix
Leak Repair and Refrigerant Recharge
A technician locates the leak, repairs it, and restores refrigerant to the manufacturer's specified level. The system must be fully thawed before refrigerant is added or readings won't be accurate.
Blocked or Closed Supply Vents
Closing vents in unused rooms seems like it would save energy, but it actually reduces airflow across the coil and can push it below freezing. Many Plano homes built after 2000 have zoned layouts where homeowners close off vents in guest rooms or bonus rooms, not realizing it stresses the system.
The Fix
Vent Balancing and System Airflow Check
Open all supply vents and let the system thaw. A technician can measure airflow at each vent and adjust the system to make sure air moves correctly through the whole house.
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 | Restricted Airflow from a Dirty Filter | Low Refrigerant Pressure | Blocked or Closed Supply Vents |
|---|---|---|---|
| Filter is visibly gray and clogged with debris | |||
| Multiple vents in the house are closed or covered | |||
| Refrigerant pressure reads below spec on gauges | |||
| Ice returns after thawing and replacing the filter | |||
| Airflow is weak throughout the whole house, not just one room |
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