Most Common AC Problems (And What to Do About Each One)

Your AC is running, but the air coming out is warm. Or the system won’t start at all. Or there’s a puddle forming next to the air handler. Whatever brought you here, you’ve found the right page.

We’ve been diagnosing air conditioning problems across Las Vegas since 2014, and the same issues show up every single summer. Not generic problems, but specific ones that hit Summerlin ranch homes, Henderson two-stories, and Spring Valley condos because of how this desert environment treats mechanical equipment. This is what our techs would tell you if they were standing in your living room right now.

Your AC System Won’t Turn On

This is the call we get most often in late May. A homeowner in Henderson flips the thermostat to cooling mode for the first time since October, and nothing happens. Nine times out of ten, the fix takes under five minutes.

Check Thermostat Settings and Dead Batteries

Replace the thermostat batteries if the unit is battery-powered. Dead batteries cause more “my AC is broken” calls than we can count. Confirm the settings show cooling mode and that the target temperature is a few degrees below the current room temperature.

Also, verify that the outdoor condenser unit is connected to its power source. After a winter maintenance visit or yard project, the disconnect switch sometimes gets left off. It is a 10-second check that saves a service call.

Breaker Box and Electric Control Failure

A tripped circuit breaker is one of the most frequent reasons an AC unit goes completely unresponsive. Running air conditioning for six-plus months straight in Las Vegas puts the electrical system under sustained stress. Capacitor failures are especially common here since heat above 100°F shortens their lifespan fast.

Reset the breaker once. If it trips again immediately, stop and call our team. Loose wiring, worn electrical connections, and electric control failure inside the air handler or compressor all carry high voltage and require a certified HVAC professional to fix safely.

Your AC Runs but Won’t Blow Cold Air

Dirty Filters and Restricted Airflow

A dirty air filter is the single most common reason we walk into a home where the AC unit is running but not pushing out cold air. Packed dirty filters restrict airflow through the system, which causes the evaporator coil to freeze over and kills cooling power entirely.

Las Vegas filters load up fast. Mojave Desert dust, active construction across the northwest and southwest valley, and seasonal wind events blow fine particulate directly into return air grilles. Replacing air filters every 30 days during summer is our standard recommendation here, not the 90-day mark on the packaging.

For most Las Vegas homes, a MERV 8 to MERV 11 filter captures desert dust without choking airflow. Going above MERV 13 in a standard residential AC unit restricts airflow enough to trigger the same frozen coil problems you are trying to prevent.

Leaky ducts are another cause of uneven cooling. When duct joints separate in the attic, the system pulls in air that regularly exceeds 150°F in a Las Vegas summer and mixes it with conditioned air before it reaches the vents.

Refrigerant Levels and AC Refrigerant Leak

Low refrigerant levels develop slowly. Cooling power fades week by week, the system runs longer to compensate, and high energy bills show up before most homeowners connect the dots.

Refrigerant circulates in a closed loop inside the AC unit. If the level is low, there is a leak somewhere. An AC refrigerant leak needs to be found and sealed rather than topped off. Any contractor who adds refrigerant without locating the source is charging you twice for the same problem.

Under the Clean Air Act, only an EPA Section 608 certified technician can legally handle or recover refrigerant. Every technician on our team carries that certification. A malfunctioning compressor stops refrigerant from circulating entirely, and when it fails, the AC stops producing cool air regardless of what else is working.

Your Evaporator Coil Is Freezing Up

Ice on the indoor coil surprises most homeowners. Air conditioner freezing has nothing to do with outdoor temperature. It is entirely about what is happening inside the system.

Restricted Airflow

A clogged filter, blocked vents, or a malfunctioning blower motor all reduce the warm indoor air passing over the evaporator coil. That warm air provides the heat energy that keeps condensation from turning to solid ice. Without it, the coil drops below freezing fast.

We have walked into homes where the entire evaporator coil was encased in a block of ice because a return vent had been blocked by furniture for months. The system was running the whole time, but was not cooling anything.

Low Refrigerant

Without enough refrigerant circulating, the coil cannot absorb heat at its designed rate. The fix is finding and sealing the leak, not thawing the coil. See our guide on handling a frozen AC unit for a full walkthrough.

When the frozen evaporator coil thaws, it releases more water than the drain system can handle at once, which leads directly to the next problem.

Blocked Drain Line and Water Leaks

Water pooling near your indoor AC unit is urgent. Drywall, flooring, and attic insulation do not survive sustained water exposure, and the longer it sits, the more expensive the damage.

The most common cause is a clogged condensate drain line. Your AC pulls moisture from indoor air, and that water exits through the condensate line. In Las Vegas, algae grows in that line during monsoon season and sits clogged until water backs up and overflows. A drain overflow that sits for even a day or two can start mold growth inside the air handler cabinet, damaging indoor air quality throughout the house.

A shop vacuum over the end of the condensate drain pipe can clear a minor clog. Flushing monthly with diluted white vinegar slows algae buildup. If the leak returns within a few days, call our team.

Strange Noises and Short Cycling

Your AC should be something you barely hear. When it starts demanding attention, something has changed.

Buzzing signals a loose electrical connection or a failing outdoor fan motor. Banging points to a loose part inside the blower motor housing. A hissing sound from the outdoor unit often means a pressurized refrigerant leak at the compressor, so call us immediately.

If you smell burning, shut the AC off at the breaker right now. An overheated blower motor or wiring fault can escalate into a fire hazard. Do not restart it until we have inspected the electrical system.

Short cycling, where the system kicks on and off every few minutes without reaching the desired temperature, stresses the compressor and drives up energy bills fast. An oversized unit, a faulty thermostat sensor, or a refrigerant leak can all cause this pattern.

Regular Maintenance Prevents Most of These Problems

Every year, around late June, our phones get busiest with calls from Spring Valley and Summerlin homeowners. These neighborhoods have large concentrations of homes built in the late 1990s and early 2000s, and those systems are aging into their most failure-prone years right as summer heat peaks. In almost every case, the unit has not been serviced since the previous summer.

Scheduling a tune-up in April or early May keeps your system running efficiently before the valley’s peak heat arrives. Our technicians clean the dirty condenser coils, check refrigerant levels, test the blower motor, flush the drain line, and inspect every electrical connection.

In Las Vegas, the outdoor condenser faces threats that generic guides ignore. We regularly find units coated in Palo Verde seed pods, packed with haboob dust, or scaled with hard water deposits from a misaligned sprinkler hitting the fins directly. To clean the fins safely, turn the unit off at the disconnect box and rinse with a garden hose on a gentle setting from the inside out. Never use a pressure washer, as it bends the fins permanently.

Keep the thermostat sensor away from direct sunlight and heat sources. A sensor reading the wrong temperature causes the system to short-cycle or run continuously without reaching your target.

Las Vegas Summers Don’t Wait

When temperatures hit 115°F or higher across the valley, systems start failing simultaneously, and every reputable HVAC company gets backed up fast. It is important to know that even a perfectly maintained system is typically only designed to cool your home down about 20°F to 25°F below the outdoor temperature, meaning on a 115°F July afternoon, an indoor temperature of 90°F to 95°F is normal and within design limits. Scheduling a tune-up in April is not about forcing your thermostat to 72°F during a heatwave; it is about ensuring your equipment can run reliably at its absolute physical limit without overheating, drawing excessive energy, or suffering a total compressor breakdown when you need it most.

If your AC unit is showing any of the signs covered above, our NATE-certified technicians can diagnose it the same day. We are open 7 days a week because AC emergencies do not respect weekends, especially in June and July when the valley’s heat peaks and schedules fill up fast.

Every repair we do comes with a 5-year labor warranty and a 10-year parts warranty. No hidden fees and no surprise charges on the invoice, because the last thing you need during a Las Vegas heatwave is a bill that looks different from the estimate. We serve Las Vegas, Henderson, Summerlin, North Las Vegas, Spring Valley, and the surrounding valley.