An AC that runs but does not cool the house is one of the most common summer service calls Cold Factor sees in DFW. The fix is sometimes a clogged filter that takes 60 seconds to swap. Other times it is a refrigerant leak that needs licensed repair.
The fastest way to find out is to work through six checks in order:
- Confirm the thermostat is set to Cool, not Fan
- Replace the air filter
- Clear the outdoor condenser of leaves and debris
- Look for ice on the indoor coil or refrigerant line
- Reset the breaker on the AC circuit
- Listen for clicking or buzzing at the outdoor unit
Steps one through three solve most of the calls Cold Factor takes in June. Steps four through six usually mean the system needs a technician. This guide walks each check in order. It explains the warning signs that mean stop, and shows exactly what a Cold Factor diagnostic visit looks like once a homeowner calls for help.
Why Your AC Is Running But Not Cooling
A central AC works by moving heat out of your house. Warm indoor air passes over an evaporator coil filled with cold refrigerant. The refrigerant absorbs the heat, the compressor pushes that hot refrigerant outside, and the condenser coil dumps the heat into the outdoor air. When any part of that loop breaks, the system keeps running but stops cooling.
Most cooling failures trace back to one of four root causes. Restricted airflow is the most common, usually from a dirty filter or a blocked return vent. Dirty coils are second, especially the outdoor condenser after a Texas spring storm.
Low refrigerant from a slow leak is third, which gets more common as a system passes the 10-year mark. Electrical failures like a bad capacitor or contactor make up the rest.
DFW summers stress every part of the loop harder than milder climates. Outdoor temperatures of 100°F or higher push the condenser to work near its design limit for weeks at a time. High humidity in late June and July pulls more moisture out of indoor air, which loads the coil and the condensate drain.
Dust from spring storms fouls the outdoor unit faster than in cleaner climates. Most AC systems in DFW give up around year 13 to 14 because they simply run more cooling hours than units in other states.
The good news is that the four most common causes are the four cheapest fixes. A homeowner can rule them out in 20 minutes before paying for a service call.
AC Not Cooling: 6 Steps to Troubleshoot
Work through the checks in order. Each one rules out a cause before you move on, and the order matches the diagnostic sequence a Cold Factor technician would follow. Stop and call for service if you reach a step you are not comfortable with.
- Check the thermostat. Confirm the mode is set to Cool and not Fan or Off. Set the target temperature at least 5 degrees below the current room temperature. Replace the batteries if the screen looks dim. A thermostat set to Fan blows room-temperature air through the vents without engaging the compressor.
- Replace the air filter. Pull the filter from the return air grille or the air handler. Hold it up to a light. Replace it if you cannot see through it. A choked filter restricts airflow and freezes the evaporator coil, which stops cooling completely. EnergyStar recommends changing the filter every 3 months at minimum, and every 60 days through DFW summer.
- Clear the outdoor condenser. Walk to the outdoor unit. Pull away leaves and grass clippings, plus any tall weeds growing within 2 feet of the unit. Spray the condenser fins gently with a garden hose from the inside out to wash off dust. A condenser caked in debris cannot dump heat and the whole system loses capacity.
- Look for ice. Open the access panel on the indoor air handler if the cover comes off easily. Check the copper refrigerant line where it enters the unit. Ice on the coil or on the copper line means the system has frozen up. Turn the thermostat to Off and the fan to On for 2 hours to let the ice melt completely before running cooling again.
- Reset the breaker. Open the main electrical panel. Find the breaker labelled for the AC or outdoor unit. Flip it fully off, count to 30, then flip it fully back on. A breaker that immediately trips again is a sign of an electrical short downstream, which needs a technician.
- Listen at the outdoor unit. Walk back to the condenser with the system running. The outdoor fan should be spinning and the compressor should hum quietly. A clicking sound followed by silence often means a failed start capacitor. A loud buzz with no fan movement usually means the same. Capacitors are inexpensive parts but they sit on 240 volts of live current, so this is a technician job.
If the AC still does not cool after these six checks, the problem is one of the deeper failures. Low refrigerant from a slow leak is the most common, followed by a frozen coil that keeps refreezing. A failed capacitor is another likely suspect, and a dying compressor is possible on systems over 12 years old. None of those are safe DIY diagnostics.
When to Call a Professional if Your AC Isn’t Cooling
Some symptoms mean the homeowner should stop troubleshooting and call for service before doing more damage. A compressor running without cooling for hours can burn itself out. A frozen coil that keeps refreezing usually has a refrigerant leak underneath it, which gets worse the longer the system runs.
Call Cold Factor when any of these are true:
- The breaker trips again within minutes of being reset
- Ice keeps forming after a full thaw and filter change
- The outdoor fan is not spinning at all
- The indoor unit is leaking water onto the floor or ceiling
- The system is more than 10 years old and the bill has been climbing
- There is a hissing sound near the indoor coil, which can mean a refrigerant leak
- The supply air feels only slightly cooler than room temperature after 30 minutes
Older R-22 systems deserve special caution. R-22 refrigerant was phased out in 2020 and is now expensive and harder to source. A leak on an R-22 system often costs more to recharge than the unit is worth, and replacement becomes the smarter signal to act on.
Running a malfunctioning AC also costs money in another way. The system pulls full electrical draw whether it cools or not. A unit that runs flat-out without cooling for a week can add $40 to $60 to the electric bill on top of the eventual repair cost.
What Happens When You Call Cold Factor
A Cold Factor diagnostic for an AC not cooling follows a predictable methodology. Knowing what a thorough visit looks like helps you spot a quality diagnostic vs a quick parts swap.
The indoor walkthrough. The technician starts at the thermostat to confirm settings, then pulls the filter to inspect airflow. They open the air handler to check the evaporator coil for ice or dust buildup. They also check for biological growth on the coil surface.
A temperature reading at the supply vents and the return grille follows. The difference between those two readings, called the delta-T, should sit between 18 and 22°F on a healthy system in DFW conditions. A delta-T below that range usually points to a refrigerant or airflow problem.
The outdoor walkthrough. The technician moves to the outdoor unit and inspects the condenser coil for debris. They check the fan blades for spin and balance. The start and run capacitors get tested with a multimeter.
Pressure gauges then connect to the refrigerant ports to read suction and discharge pressures. Low pressures usually mean a refrigerant leak. High pressures usually mean a dirty condenser or a failing compressor.
The findings conversation. The technician brings the readings back inside and explains what they found before any repair starts. You get a written estimate that lists exactly what is wrong and what parts and labour will cost. Any alternative options are spelled out at the same time.
For a system close to end of life, this is when the repair-or-replace conversation happens. A Cold Factor maintenance visit aims to give an honest read on whether the repair investment makes sense or whether replacement is the better long-term call.
The repair or the quote. Simple fixes like a capacitor replacement or a coil cleaning happen on the spot. Larger work like a refrigerant leak repair or a compressor swap gets scheduled separately with parts on order. Ask about a membership plan if the system is your second cooling-failure call this year, since regular maintenance catches most of these problems before they strand you in August.
Book a Cold Factor AC Diagnostic
When the six checks have not brought back cool air, a Cold Factor diagnostic finds the real cause and gets the system back online. Crews cover Lewisville, Allen, Coppell, The Colony, Roanoke, Southlake and Highland Village with same-day availability in peak summer.
Ask about combining the diagnostic with a full system tune-up if the unit is over 5 years old and has not been serviced this year. Check current specials before you book.