Home › Common Problems › AC Frozen Up
AC Frozen Up
in Tempe, AZ
Ice forming on your AC unit seems strange when it is 110 degrees outside in Tempe, but it happens more often than people expect. Low airflow or low refrigerant causes the coil to drop below freezing even in summer heat. If you keep running the system, the ice can spread into the blower and cause water damage when it eventually melts.
Quick Answer
A frozen AC in Tempe is almost always caused by a dirty air filter or low refrigerant. The fix starts with turning the system off and letting the ice melt completely, which takes a few hours. Then a technician checks airflow and refrigerant. Call (928) 564-6468 before you restart the system — running it while frozen can damage the compressor.
Telltale Signs
Warning Signs to Watch For
- Ice visible on the copper refrigerant lines near the indoor unit
- Water dripping or pooling around the base of the air handler
- Airflow from the vents drops off noticeably
- The system runs but the house does not cool down
- A crunching or gurgling sound coming from the indoor unit
Root Causes
What Causes AC Frozen Up?
Restricted Airflow From Filter
When airflow across the indoor coil drops, the coil gets too cold and freezes the moisture in the air around it. In Tempe, dust storms from the west side of the valley hit regularly in July and August, and they load up a filter in days rather than months. A clogged filter is the most common reason a system freezes up.
The Fix
Filter Replacement and Airflow Check
Replace the filter and let the ice thaw with the fan running on the fan-only setting. A technician should also check that all supply vents in the house are open and unblocked.
Low Refrigerant Level
Low refrigerant causes the evaporator coil to run at a much lower pressure than it should. That drops the coil temperature below freezing, and ice builds up on the coil surface. Tempe homes built in the 1980s often have older systems with worn Schrader valves or flare fittings that develop slow leaks over time.
The Fix
Leak Detection and Refrigerant Recharge
A technician finds the leak with electronic leak detection, repairs it, and brings the system back to the correct charge. Just adding refrigerant without finding the leak means the ice problem returns.
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 Filter | Low Refrigerant Level |
|---|---|---|
| Filter is gray and clogged with dust | ||
| Ice on lines even with a clean filter | ||
| Airflow from vents is very weak | ||
| Oily staining near refrigerant line connections | ||
| System freezes up repeatedly after filter changes |
Free Inspection
Get a Diagnosis in Tempe
An on-site inspection is the only way to confirm which cause applies to your property. Free, no obligation.
(928) 564-6468Free on-site inspection
Written estimate before work starts
Serving Tempe & surrounding areas
Other Problems
Services That Fix This
Also Helpful