Ice on the evaporator coil or refrigerant lines is what a frozen AC coil in Las Vegas, NV 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 77 ZIP codes around Las Vegas 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 |
|---|---|---|
| Dirty filter or blocked return | Low airflow lets the coil get too cold | You, or a technician |
| Dirty evaporator coil | Dust blocks airflow through the fins | Technician |
| Failing blower motor or capacitor | The fan moves too little air | Technician |
| Cooling in cool weather | Low outdoor temperatures can freeze a coil | Switch to off and use heat or fan |
| Low refrigerant | Pressure falls and the coil temperature drops below freezing | Technician, with a leak repair |
| 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
- Keep supply and return registers open and clear
- Have the coil cleaned and the blower tested during a tune-up
- Fix refrigerant leaks instead of topping up
- Do not set the thermostat far below the room temperature on mild days
- Change the filter on schedule and use the right size
What the technician will check
- Condition of the evaporator coil and the drain
- Refrigerant pressures, superheat and subcooling, and a leak search
- Temperature drop across the coil and static pressure
- Filter, registers and ductwork for restrictions
- Blower motor, capacitor and fan speed
Ducts, airflow and comfort
Even a sound system leaves hot rooms when ducts leak, returns are undersized or registers are blocked, because comfort depends on airflow as much as capacity. These problems show up when a technician measures static pressure and airflow instead of only refrigerant pressures.
A checklist for this week
- Inspect the drain line outlet and the area around the air handler for water
- Test the thermostat and schedule
- Write down any noises or smells
- Clear the outdoor unit of debris
- Book a tune-up if it has been more than a year
- Check supply and return registers
- Replace the filter and note the date
HVAC terms explained
- Condenser coil: the outdoor coil where heat is released
- Evaporator coil: the indoor coil where refrigerant absorbs heat from the air
- Condensate drain: the line that carries moisture out of the house
- Superheat and subcooling: readings that show whether the refrigerant charge is correct
- Contactor: the switch that sends power to the outdoor unit
- Static pressure: a measure of airflow resistance in the ducts
- EPA Section 608: the certification required to handle refrigerants
Myths and facts
- Myth: refrigerant is used up. Fact: low refrigerant means a leak.
- Myth: maintenance is optional. Fact: dirty coils and weak capacitors cause many summer failures.
- Myth: set the thermostat very low to cool faster. Fact: the AC cools at a steady rate and just runs longer.
- Myth: a bigger AC is always better. Fact: oversizing causes short cycling and humidity problems.
- Myth: closing vents saves energy. Fact: it raises duct pressure and can cause leaks and noise.
What shapes the written scope
Do not judge an AC job by how the call sounds, since two similar complaints can lead to very different work. Look for a written scope that states the technician's findings and the factors that applied.
Ask the provider to separate the diagnostic from the repair, and to list any parts, labor or follow-up that are not included.
- The age, tonnage and refrigerant type of the system
- Whether the ductwork, return air or thermostat contributes to the problem
- Warranty status of the parts and whether the equipment is registered with the manufacturer
- Whether the fault is an electrical part, an airflow problem, a refrigerant leak or a drainage problem
- Access to the air handler in the attic or closet and to the outdoor unit
When to call a professional
Pick up the phone if the system will not start, if ice or water shows up, if the same problem comes back after your own checks, if you hear grinding or banging, or if anyone at home is vulnerable to heat or cold. Call Now at the top of the page puts you through once you describe what the system is doing: an independent HVAC contractor covering your ZIP code confirms the address and diagnoses the system in person.
What this means for a home in Las Vegas
Extreme desert heat with summer highs above 105 degrees and long cooling seasons; attics are far hotter than the air outside. Monsoon moisture in July to September adds humidity spikes.
Nevada contractors are licensed by the Nevada State Contractors Board; refrigeration and air conditioning is the C-21 classification. Dust and sun exposure clog and age condenser coils; many systems last about 10 to 15 years in extreme heat. Use these local details when you compare advice, and ask any technician how they apply to your system and your house.
Getting help in Las Vegas and nearby cities
Through Air Conditioning Installation Las Vegas, you can reach independent HVAC contractors serving 77 ZIP codes in Las Vegas, Nevada: 89101, 89102, 89103, 89104, 89105, 89106, 89107, 89108, 89109, 89110. Requests also go to providers in North Las Vegas, Henderson and Boulder City, and coverage is checked for each address individually.
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 Las Vegas homeowners: What Size AC Do You Need? Tonnage and Load Calculation; SEER2 Explained for Las Vegas Homeowners; AC Making Noise: What Each Sound Means; Summer HVAC Checklist for Las Vegas. 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?
Turn the cooling off and let the fan run so the ice melts by itself; tools that apply heat risk damaging the coil or the lines.
Can I keep the AC running with ice on it?
Not safely; compressor damage and water damage are risks of running a frozen system.
Is a frozen coil an emergency?
It should be addressed quickly, but it is not an emergency unless there is a risk of water damage or vulnerable occupants.
How long does the ice take to melt?
Several hours up to a day depending on the buildup.
Will a new filter fix it?
A new filter fixes it when a dirty filter was the cause, and a technician should be called if ice comes back.