Ice on the copper line in a Jacksonville August: the first hour, and the next six
Few sights in a Jacksonville garage are stranger than a block of ice on a copper pipe during the hottest week of the year. Here is how that day unfolds, and how to make it a short one.
1:40 p.m.: the sound changes
Picture a Thursday in the second week of August in Oceanway, highs forecast for 96 and the dew point sitting at 74. The air conditioner has been running since 10 a.m. without stopping, which is normal for the week. Then the sound shifts. The blower is still going but the registers have gone quiet; barely any air moves at the bedroom vent. The thermostat reads 78 and climbing.
The homeowner goes to the garage. The copper suction line coming out of the air handler is white with frost from the cabinet to the wall, and the bottom of the cabinet is wearing a skirt of ice. Water is dripping onto the garage floor from the melt.
1:45 p.m.: the only right move
Turn the thermostat from cool to off. Then set the fan to on. That stops the refrigerant cycle so the coil can warm, and keeps room air moving across it to melt the ice from inside. Do nothing else to the ice. Put a towel or a pan under the air handler, because the next few hours will produce more water than the drain pan expects, and a secondary pan with a float switch may already be filling.
Then pull the filter. In this house it is a one-inch pleated filter last changed in March, before the pines finished. It is gray, heavy and nearly opaque to a flashlight. That is the first suspect.
Why Jacksonville freezes more coils than it should
A coil freezes when its surface drops below 32 degrees, which happens when too little warm air crosses it (airflow) or too little refrigerant flows through it (charge). Two local factors tilt the odds.
Pollen season loads the filter and the coil. Oak from late February, pine through April, a layer of fine dust on the coil fins that a one-inch filter never caught. By August the coil itself is a felt pad, and airflow has been dropping for months.
Humidity feeds the ice. With dew points in the low 70s, the air carries a great deal of water. Once the coil surface dips below freezing, that water does not just condense and drain; it freezes, layer on layer, and each layer blocks more air, which makes the coil colder. A coil in a dry climate frosts; a coil in Jacksonville builds a glacier in ninety minutes.
Add the usual mechanical causes: a blower motor slowing with age in a twenty-year-old Oceanway system, a return undersized for a retrofitted Springfield bungalow, a slow refrigerant leak on a salt-corroded Jacksonville Beach condenser, a thermostat left at 68 overnight by someone trying to catch up.
4:30 p.m.: the thaw, and the question
Three hours in, the ice is gone and the garage floor is wet. The temptation is to switch cooling back on and declare victory. Sometimes that works for a week. But a coil that froze once on a clogged filter will freeze again on a dirty coil, and a coil that froze on low charge will freeze again tomorrow.
The honest decision point: if the filter was obviously the cause and the system restarts with strong airflow and cold air, run it and schedule a coil cleaning soon. If airflow is still weak, if the air is cool but not cold, or if the ice comes back within a day, stop and call.
6:15 p.m.: the visit
We work Jacksonville from the Palm Coast headquarters, an hour and a quarter up I-95, and an evening call costs what a morning call costs. The frozen-coil visit has a fixed order:
- Airflow. Filter, return size, blower speed and amperage, static pressure across the coil. This finds the cause in most Jacksonville homes.
- The coil itself. Pulled or inspected in place; cleaned if it is matted. A coil that has been fouled for years sometimes needs replacing, not cleaning.
- Refrigerant. Pressures and temperatures once the system has run clean for twenty minutes. Low charge means a leak search, not a top-off.
- Drainage. The pan, trap and float switch, because a thaw puts more water through them than any normal day.
- The fix and the prevention. Usually a coil cleaning plus a deeper filter cabinet, or a return enlargement on an urban-core house. Occasionally a leak repair. Rarely, on a system past twenty years with a leaking coil, the replacement conversation.
By 8 p.m. the Oceanway house is at 76 degrees and the registers are loud again. The filter cabinet goes in the following week, before the next pollen season has a chance.
Frozen-coil questions from Duval County
How can ice form when it is 95 degrees outside?
The coil’s refrigerant runs well below freezing. Normally warm, moving air keeps the coil surface above 32 degrees; when airflow drops or the charge is low, the surface falls below freezing and Jacksonville’s humid air condenses and freezes on it in layers.
Can I chip the ice off to speed things up?
No. The fins and tubing bend and puncture easily, and a punctured coil turns a filter problem into a coil replacement. Let it thaw with the fan running; it takes two to four hours in a Jacksonville garage.
Why does this keep happening every summer in my Riverside house?
Retrofitted systems in 1920s houses often have returns far too small for the blower. Every summer the filter loads with pollen, the already-marginal airflow drops below the line, and the coil ices. The cure is a bigger return, not another thaw.
Is a frozen coil an emergency?
Not in the first hours, if you turn cooling off and let it thaw. It becomes one if you keep running it frozen, because liquid refrigerant returning to the compressor can destroy it. Turn it off; call when it is convenient.
Thawing it is the easy part
Finding why it froze is ours. Call {{phone}}, day or night, same price either way.