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What To Do If Your Air Conditioner Blows Out Warm Air

Serving Families Throughout Dallas
man checking airflow out of air vent

The air flowing out of your air vents should feel refreshing and cool. When it feels warm or lukewarm, you know there’s a problem. While you may need to contact an HVAC technician, the good news is that you can sometimes troubleshoot this issue and fix it yourself.


In Dallas, a malfunctioning air conditioner can quickly turn a comfortable space into an uncomfortable one, especially during the scorching summer months. One of the main reasons that an air conditioner will blow lukewarm air is that the air filter is clogged. While this is often the problem we see, there are also several other common issues could cause your AC to blow warm air instead of cool relief:

- Low refrigerant levels diminishing cooling capacity
- Dirty or damaged compressor or condenser coils impeding effective cooling
- Problems with the thermostat or electrical system resulting in inaccurate temperature control.

Addressing these issues promptly through professional maintenance and repair services is crucial for restoring your AC's cooling performance and ensuring comfort in your home or workspace.


1. Check the thermostat.

Even if you think your thermostat is set correctly, check it anyway, especially if you live in a home with others who may have “adjusted” the thermostat. It’s possible that only your air conditioning system’s fan is running and circulating warm air throughout your home.

If your thermostat says “on,” then that means the system’s fan is on. This means that the fan will keep pushing air through the ducts and out of the vents even when the indoor unit isn’t cooling it. Your thermostat needs to be set to “cool” or “auto” for your AC to cool and dehumidify your indoor air while the fan circulates it.

2. Make sure the outdoor unit has power.

Your air conditioner is a high-powered appliance, meaning it draws a lot of power to operate. If there’s a momentary power surge, this can cause your outdoor unit to trip the circuit breaker. If your AC is blowing out warm air, check your circuit breaker panel for a tripped switch.

Also, if your AC unit has been worked on recently, the technician most likely turned off the outdoor unit at some point while performing the work. The technician may have forgotten to turn the outdoor unit back on, so check the box on the wall outside next to your unit to make sure the equipment is receiving power.

3. Make sure nothing is crowding the outdoor unit.

Your air conditioner’s outdoor unit (the condenser) releases heat. Therefore, it needs room for ventilation on its sides and on top. (This is one of the reasons why we cringe whenever we see a unit installed under a deck or crawlspace.) Ensure the condenser has at least 1 foot of space around it and at least 5 feet of vertical clearance. Pull any weeds and trim back any shrubs or hedges growing against the equipment.

See Also: Landscaping Dos and Don’ts Around Your Outdoor AC Unit

4. Check the air filter.

Most manufacturers say that disposable air filters are good for up to 90 days—the key phrase being “up to.” If you’re using your air conditioner throughout the day for weeks on end, that filter is going to get dirty way before 90 days are up. If you own pets, the filter will get dirty even faster.

So how does a dirty air filter cause warm air to come from an air conditioner? When an air filter becomes coated with dust, it blocks airflow through your air conditioning system. This creates some problems:

  • The air conditioner needs to work extra hard to send out cool air.
  • Not enough hot air blows over the indoor coil (aka. evaporator coil), which contains refrigerant.

As a result, parts of your AC can overheat, while the condensation on the evaporator coil can freeze. Once the coil has iced over, it can’t cool your indoor air effectively. Furthermore, a frozen evaporator coil puts the system’s compressor in danger of overheating and dying.

If a layer of ice has formed over your evaporator coil, you must put in a new filter and allow the ice to melt. Let your HVAC system’s fan run to help speed up thawing, but make sure the “cool” setting is off. Once the ice is gone, you can resume using your AC, although you may want to have a technician inspect the equipment for any problems. If you start using your system again and the ice returns, shut off your system and contact an HVAC technician to inspect the system for a possible refrigerant issue.


If these troubleshooting steps above fail to solve your air conditioning problem, you’ll need to involve an HVAC professional. At this point, the cooling issue will most likely stem from one of these three problems:

  • There’s a refrigerant leak.
  • The fan in the condenser is failing.
  • The system needs a new compressor.

At Rescue Air and Plumbing, our trained and experienced HVAC technicians are experts at getting to the root of our customers’ heating and cooling issues and providing quality solutions.

Contact us online today or give us a call at (972) 201-3253 for AC repair in the Dallas-Fort Worth Metro.