The evaporator runs just above freezing so that moisture condenses on it and drains away as water. When too little warm air crosses the coil, or too little refrigerant flows through it, its temperature drops below 32°F and that moisture freezes into a sheet.
Service · Alhambra, CA
Frozen AC Coil / AC Leaking Water in Alhambra, CA
Ice on a refrigerant line or water on a ceiling means the cooling cycle is breaking its own rules, and running the system longer only makes the fault worse. Both come from the evaporator coil, and each has a short list of causes.
What you are seeing
Frost, drips and stains: what you are seeing
- Frost on the line
A white sleeve of ice on the larger copper line outside or in the attic.
- Weak airflow
Vents that blow less and less because ice is filling the coil fins.
- Water at the air handler
Drips from the pan, a wet closet floor or a brown ceiling stain below the attic.
How it works
Why a coil that should be cold enough becomes too cold
Ice then insulates the coil, airflow falls further, and the cycle feeds itself. When the ice finally melts, the drain pan receives far more water than its line can carry.
Property type
Attic air handlers that flood the ceiling below
Where an Alhambra bungalow has its air handler in the attic, a backed-up condensate line empties into the secondary pan and then through the ceiling. By the time the stain is visible, insulation and drywall are already wet.
- Clogged drain line
Algae slime plugs the narrow trap over a season of damp operation.
- Cracked or rusted pan
Old galvanized pans corrode through at the seams.
- Float switch
A working safety switch stops the system before water spills; a failed one does not.
Technique
How a frozen or leaking system is handled
Stop and thaw
The cooling is switched off and the blower is left running so air melts the ice.
Drain the water
Standing water is removed from the pan and the condensate line is cleared.
Check airflow
Filter, blower speed, return grille and the attic duct runs for kinks or crushing.
Read the circuit
Pressures and temperatures show whether low charge, not airflow, started the freeze.
Repair and retest
The cause is corrected and the coil is watched through a full cycle.
Say where the ice or water appears and how long the system has been running, and the call can set the order of work.
(626) 687-0603Phase order
Why thawing comes first
A frozen coil cannot be measured accurately, so any reading taken through the ice leads to the wrong conclusion.
Thawing, draining and only then diagnosing keeps the technician from chasing a refrigerant problem that was really a clogged filter. If the same freeze returns after the airflow is corrected, the cause shifts toward a sealed-system leak.
Local detail
Humid spells and drain lines in Alhambra
Warm, damp evenings in the San Gabriel Valley make the evaporator produce more condensate than dry days do, so a drain line that was marginal in spring clogs by late summer. Los Angeles County homes with older attic pans see the leak show up on the ceiling first.
Measured results
Signs the freeze is actually solved
- Dry pan
The drain pan stays empty and the condensate line runs freely after a long cycle.
- Clean coil face
No frost forms on the evaporator or the large line after the system has run for hours.
- Healthy split
The air leaving the vents is cooler than the return air by the expected margin.
Safety protocol
Protect the house while you wait
- Cooling off, fan on
Set the thermostat to Off and the fan to On to melt the ice.
- Breaker off for water
If water is dripping near the unit or a light fixture, turn the system breaker off.
- Buckets and towels
Catch drips, and keep clear of any ceiling that is bulging with water.
- Never chip the ice
Scraping can puncture the coil.
Scope: Emergency diagnostic dispatch, whole system replacement and ductwork replacement only. Scope and pricing are provided directly by independent licensed contractors.
Common questions
Questions about a frozen AC or a water leak in Alhambra
Are Alhambra homes in 91801 covered for AC water leaks?
Covered homes are in Alhambra ZIP codes 91801, 91803 and 91804.
Why did my AC freeze up in hot weather?
A coil freezes when too little air or refrigerant crosses it, even on a 95°F day. A dirty filter, a closed register, a failing blower or a refrigerant leak can each do it.
Is it safe to run the fan to melt the ice?
Yes, with the cooling turned off. The blower moves room air across the coil and melts the ice without making more.
Does a water leak from the AC mean the drain is clogged?
Often, but not always. A cracked pan, a loose fitting or melting ice from a frozen coil can overload even a clear drain.
A heating or cooling fault rarely fixes itself.
Call and describe the problem in Alhambra: what the system is doing, what it did first and how old the equipment is.