Ice on the evaporator coil or refrigerant lines is what a frozen AC coil in Memphis, TN means, and the system cannot move heat while it is there. Restricted airflow and low refrigerant are the two big causes. Before you call, turn the cooling off, let the ice melt and run through the basics below. When you want a diagnosis, use Call Now and an independent HVAC contractor serving 59 ZIP codes around Memphis will answer.
What to do right now
- Switch the thermostat from cool to off and set the fan to on so warm indoor air melts the ice
- Give it several hours. A heavy coil can take most of a day to thaw, so do not chip the ice
- Place towels or a pan under the air handler, because melting ice makes a lot of water
- Replace the filter if it is dirty and open all supply and return registers
- Do not restart cooling until the ice is gone
Why a coil freezes
| Cause | How it freezes the coil | Who fixes it |
|---|---|---|
| Low refrigerant | Pressure falls and the coil temperature drops below freezing | Technician, with a leak repair |
| Cooling in cool weather | Low outdoor temperatures can freeze a coil | Switch to off and use heat or fan |
| Dirty evaporator coil | Dust blocks airflow through the fins | Technician |
| Failing blower motor or capacitor | The fan moves too little air | Technician |
| Dirty filter or blocked return | Low airflow lets the coil get too cold | You, or a technician |
| Closed or blocked supply registers | Airflow drops and pressure rises | You |
What a frozen coil can damage
Water from melting ice may overflow the drain pan onto ceilings, insulation and floors, and liquid refrigerant that reaches the compressor through a frozen coil can damage it. Stop the system and call if you see ice on the outdoor lines or find the compressor cold and sweating.
Prevent it from coming back
- Fix refrigerant leaks instead of topping up
- Change the filter on schedule and use the right size
- Have the coil cleaned and the blower tested during a tune-up
- Do not set the thermostat far below the room temperature on mild days
- Keep supply and return registers open and clear
What the technician will check
- Filter, registers and ductwork for restrictions
- Blower motor, capacitor and fan speed
- Temperature drop across the coil and static pressure
- Condition of the evaporator coil and the drain
- Refrigerant pressures, superheat and subcooling, and a leak search
HVAC terms explained
- Static pressure: a measure of airflow resistance in the ducts
- Contactor: the switch that sends power to the outdoor unit
- Capacitor: stores charge to start and run the compressor and fan motors
- Evaporator coil: the indoor coil where refrigerant absorbs heat from the air
- EPA Section 608: the certification required to handle refrigerants
- Superheat and subcooling: readings that show whether the refrigerant charge is correct
- Condenser coil: the outdoor coil where heat is released
- Condensate drain: the line that carries moisture out of the house
Ducts, airflow and comfort
Comfort depends on airflow as much as on cooling capacity. Leaky ducts, undersized returns and blocked registers cause hot rooms even when the system is sound. A technician who measures static pressure and airflow, not just refrigerant pressures, will find these problems.
A checklist for this week
- Clear the outdoor unit of debris
- Inspect the drain line outlet and the area around the air handler for water
- Book a tune-up if it has been more than a year
- Test the thermostat and schedule
- Write down any noises or smells
- Check supply and return registers
Myths and facts
- Myth: maintenance is optional. Fact: dirty coils and weak capacitors cause many summer failures.
- Myth: a bigger AC is always better. Fact: oversizing causes short cycling and humidity problems.
- Myth: set the thermostat very low to cool faster. Fact: the AC cools at a steady rate and just runs longer.
- Myth: refrigerant is used up. Fact: low refrigerant means a leak.
- Myth: closing vents saves energy. Fact: it raises duct pressure and can cause leaks and noise.
What shapes the written scope
Two AC calls that sound alike can be very different jobs. The written scope should say what the technician found and which of these factors applied.
Have the provider show the diagnostic and the repair as separate items, and list any parts, labor or follow-up that are left out.
- Whether the ductwork, return air or thermostat contributes to the problem
- The age, tonnage and refrigerant type of the system
- Access to the air handler in the attic or closet and to the outdoor unit
- Whether the fault is an electrical part, an airflow problem, a refrigerant leak or a drainage problem
- Warranty status of the parts and whether the equipment is registered with the manufacturer
Safety and rules to know
Three hazards share one machine in an air conditioner: high-voltage electricity, pressurized refrigerant and moving parts. Opening electrical panels, bridging contactors and adding refrigerant are not jobs for homeowners, and capacitors can keep a charge after the power is off.
In the United States, anyone who buys or handles refrigerant must be certified under EPA Section 608, and refrigerant must be recovered and not vented. Ask the technician for their certification and check the contractor's licence with Tennessee Board for Licensing Contractors (HVAC classifications).
When to call a professional
Several situations call for a contractor: a system that will not start, ice or water, a problem that returns after your own checks, grinding or banging noises, or anyone in the house who is vulnerable to heat or cold. Use Call Now at the top of the page, describe what the system is doing, and you will reach an independent HVAC contractor who covers your ZIP code, confirms the address and diagnoses the system in person.
What this means for a home in Memphis
Hot, humid Mid-South summers with heat indexes often above 100 degrees; winters can bring ice storms. Humidity drives condensate drain clogs, sweating ducts, and mold in air handlers.
Memphis Light, Gas and Water (MLGW) is the local utility. Older homes in Midtown, Cooper-Young, Binghampton, and Whitehaven; newer homes in Cordova, Collierville, Germantown, and Bartlett. Bring these local details into any comparison of advice, and ask each technician how they apply to your system and your house.
Getting help in Memphis and nearby cities
Independent HVAC contractors covering 59 ZIP codes in Memphis, Tennessee are reached through Air Conditioning Repair Memphis: 37501, 37544, 38101, 38103, 38104, 38105, 38106, 38107, 38108, 38109. Providers who serve Ellendale, Germantown, Cordova and Collierville can also receive requests. Each address is confirmed separately.
Start with Call Now at the top of the page and say what you have found. The contractor checks your address, looks over the system and gives you the scope in writing.
Keep reading
Related pages for Memphis homeowners: What Size AC Do You Need? Tonnage and Load Calculation; AC Not Cooling? 12 Causes and Fixes; SEER2 Explained for Memphis Homeowners; How to Lower Cooling Bills. For the area list, see the service areas page.
Common questions about frozen AC coil: why it happens and what to do
Why is there ice on my AC?
Ice usually means low airflow or low refrigerant. A dirty filter, blocked registers, a weak blower or a leak can cause it.
Can I use a hair dryer to melt the ice?
It is safer to turn cooling off, run the fan and let it melt. Heat tools can damage the coil or lines.
Can I keep the AC running with ice on it?
No, because a frozen system that keeps running risks harm to the compressor and water damage.
Is a frozen coil an emergency?
Deal with it quickly, though it only becomes an emergency if water damage is a risk or someone vulnerable lives in the house.
How long does the ice take to melt?
From several hours to a day, depending on how much ice has built up.
Will a new filter fix it?
It will if a dirty filter was the cause. If ice returns, call a technician.