Troubleshooting guide for when your AC is running but not keeping your home cool enough.
Your AC Runs But the House Won't Cool Down
This is one of the most frustrating HVAC problems — your system is running, the fan is blowing, but the temperature inside keeps climbing. In Oklahoma's extreme heat (regularly 100°F+), even a healthy AC system works hard. But if it can't maintain your set temperature within 3-5 degrees, something is wrong.
Most Common Causes
Dirty air filter is the number one cause — a clogged filter restricts airflow so severely that the evaporator coil can't absorb enough heat. Replace it and wait 30 minutes to see improvement. Low refrigerant from a leak is the second most common cause — the system runs but can't transfer enough heat outside. A dirty outdoor condenser coil covered in cottonwood fluff, grass, or dust can't release heat effectively. Leaky ductwork in attics or crawl spaces can lose 20-30% of cooled air before it reaches your rooms.
Oklahoma-Specific Issues
Oklahoma's combination of extreme heat and high humidity makes cooling harder than in dry climates. Your AC has to remove moisture AND lower temperature. On days above 105°F, even a properly functioning system may struggle to maintain 72°F — setting it to 75-78°F during extreme heat is more realistic and prevents the system from running constantly.
When Your System Is Undersized
If your house was built in the 1970s-80s with the original AC, it's likely undersized by today's standards. Additions, new windows, or poor insulation can also make a system that was once adequate too small. ARP Heat And Air can perform a load calculation to determine if your system is properly sized for your home.
At ARP Heat And Air, we've been helping Oklahoma homeowners with their HVAC needs since 2011. Our owner Charlie brings 14+ years of hands-on experience and is known for giving honest, practical advice — not trying to upsell you on services you don't need.
If you have questions or need HVAC service in the OKC metro area, give us a call at (405) 413-0583. We offer free estimates, same-day service, and 24/7 emergency response.
Based in Edmond, OK, we serve 19 cities across the Oklahoma City metro area. Oklahoma CIB License #00125054.
When to DIY vs Call Service
Some AC issues are genuinely DIY. Others you should not touch because they're unsafe or make the problem worse. Here's the line.
DIY-appropriate: Filter replacement, thermostat battery swap, checking breakers, clearing debris from around the outdoor unit, cleaning the outdoor coil with a garden hose (pressure too low to damage fins), clearing the condensate drain line, adjusting thermostat settings.
Call a professional: Anything involving refrigerant, electrical work beyond resetting a breaker, capacitor replacement, motor diagnostics, compressor issues, frozen coil that doesn't thaw after 6 hours with system off, unusual smells (burning, chemical), and any repeated tripping of breakers.
Why refrigerant work is regulated: EPA Section 608 certification is legally required to handle refrigerant. Beyond the legal issue, mixing refrigerant types or undercharging/overcharging a system causes compressor damage that costs $1,500-$3,000 to repair.
Common "fixes" that actually cause damage: Pouring water or ice on an overheating condenser (cools too fast, stresses metal). Taping over a drain line (backs up into the drip pan and overflows). "Topping off" refrigerant from a cheap kit (usually wrong refrigerant type or quantity). Running the system while it's making new grinding or screeching noises (rides out bearing failure until motor seizes).