(702) 333-8057 
The air is moving, the unit is running, and the house just will not get cool. It is the single most common call we take between June and September, and in a climate where afternoons sit above 110°F, it goes from frustrating to genuinely unsafe faster than most people expect. The good news is that an AC blowing warm air is usually telling you something specific, and most of the causes are affordable repairs rather than a dead system. Here are the seven reasons we find most often on Las Vegas no-cooling calls, in roughly the order we check them. For the wider picture on diagnosis and repair, our complete AC repair guide walks through the whole process.
7 Reasons Your AC Is Running but Not Cooling
An air conditioner that runs without cooling has either lost its ability to move heat, or lost the airflow it needs to deliver cold air. These seven causes account for the overwhelming majority of what we find.
1. Dirty Air Filter
The cheapest cause and the first thing to check. A filter packed with Las Vegas dust chokes airflow, so even properly chilled air never reaches your rooms, and the coil can eventually freeze. In peak summer, check the filter monthly. This one you can often fix yourself in five minutes.
2. Low Refrigerant From a Leak
Refrigerant is what actually carries heat out of your home, so a low charge means weak, lukewarm air and very long run times. Because it circulates in a sealed loop and is never consumed, low always means a leak. It needs to be found and repaired, not just topped off.
3. Frozen Evaporator Coil
Counterintuitive in 110-degree weather, but restricted airflow or low refrigerant can drop the indoor coil below freezing until it ices over and stops cooling entirely. If you see ice on the indoor unit or the copper lines, shut cooling off, run the fan to thaw it, and call.
4. Dirty Condenser Coil
The outdoor unit has to dump your home's heat into air that is already scorching. Caked in desert dust and landscaping debris, it cannot shed that heat, so the system runs and runs while the house stays warm. A professional coil cleaning often restores full cooling on its own.
5. Failed Capacitor or Contactor
If the outdoor fan is spinning but the compressor never kicks on, you get airflow with no cooling at all. A worn capacitor or pitted contactor is the usual culprit, and it is one of the most common and most affordable repairs we make in this heat, usually done on the same visit.
6. Thermostat Problem
Sometimes the system is fine and the instructions are wrong. A miscalibrated thermostat, one mounted in afternoon sun, or one accidentally set to FAN instead of COOL will leave you with moving air that was never cooled. Always worth ruling out before assuming a mechanical failure.
7. Failing Compressor
The most serious cause and, thankfully, the least common. When the compressor cannot pump refrigerant, nothing cools no matter how long it runs. It usually follows months of an ignored low charge or a bad capacitor, which is exactly why the small stuff is worth fixing early.
What These Repairs Typically Cost in Las Vegas
Cost depends entirely on which of the seven you are dealing with. The ranges below reflect typical Las Vegas repairs including labor; the diagnostic fee is disclosed upfront before any work begins.
| Cause | Typical Cost | Notes |
|---|---|---|
| Air filter / airflow correction | $0–$75 | Often a filter change and a vent check |
| Capacitor replacement | $100–$300 | Most common repair in Las Vegas heat; usually same-visit |
| Contactor replacement | $150–$350 | Often replaced alongside the capacitor |
| Coil cleaning (indoor or condenser) | $100–$250 | Restores heat transfer; part of a full tune-up |
| Thermostat replacement | $75–$200 | Includes smart-thermostat options; setup included |
| Refrigerant leak repair + recharge | $300–$800 | Varies by leak location and refrigerant type |
| Compressor replacement | $800–$1,800 | Major repair; we weigh system age before recommending |
If the diagnosis lands on a compressor or coil failure in a system past 12 to 15 years, we will lay out the repair-versus-replace math honestly rather than selling you a repair that does not pay for itself. When replacement is genuinely the better value, a new high-efficiency installation comes with ACE's 36-month 0% financing and 90 days of zero payments to start.
When No Cooling Becomes an Emergency
Weak cooling on a mild evening can wait for a scheduled appointment. Call right away if any of these apply:
- No cooling at all with the indoor temperature climbing past 85°F
- Elderly adults, young children, or pets in the home without a cool space
- A burning or electrical smell from either unit
- Loud banging or grinding from the outdoor unit
- The breaker tripping repeatedly when the system tries to start
ACE runs 24/7 emergency service from June through September across Las Vegas, Henderson, North Las Vegas, and the communities we serve throughout the valley. Call (702) 333-8057 any time and we will prioritize by heat-safety risk.
Most No-Cooling Calls Are Preventable
Look back at the seven causes and five of them are things a pre-season tune-up catches: a dirty filter, dirty coils, a fading capacitor, a low charge, a drifting thermostat. That is why a spring visit is the cheapest insurance available against a July breakdown. Our technicians clean the coils, verify the refrigerant charge, test the capacitor and contactor, and confirm the thermostat reads correctly, so the small problems get handled on your schedule instead of on the hottest afternoon of the year.
ACE offers a $49 new-customer tune-up special and a $69 standard tune-up for existing customers. Military members and veterans, along with senior residents, receive a 10% discount on all ACE services. Not sure what your system needs? Contact our team and we will point you the right way.
AC Running but Not Cooling? We Will Find the Cause
Same-day service for most calls. 24/7 emergency response June through September. Free estimates on replacements. Financing at 0% interest for 36 months with 90 days of zero payments.
(702) 333-8057 — Call NowSchedule OnlineFrequently Asked Questions
Why is my AC running but blowing warm air?
Warm air from a running system almost always means the unit has lost its ability to move heat or its airflow. The most frequent causes are a low refrigerant charge from a leak, a dirty condenser coil that cannot shed heat, or a failed capacitor that keeps the compressor from starting while the fan still runs. A clogged filter is also common and is the one worth checking yourself first.
Should I turn my AC off if it is not cooling?
Usually yes, at least until it is diagnosed. Running a system that is not cooling wastes electricity and, if the cause is a frozen coil or a failing compressor, can turn a moderate repair into an expensive one. If you see ice on the unit, switch the thermostat to off and set the fan to ON so the coil can thaw, then call a technician.
How quickly can ACE get out for a no-cooling call?
Same-day service is available for most standard calls placed on weekday mornings across the Las Vegas valley. Peak-season call volume is heavy, so calling early in the day improves your odds. For a complete failure or a household with vulnerable residents, use the 24/7 emergency line at (702) 333-8057 and we will prioritize accordingly.