The short answer
When an AC runs nonstop but the house will not cool, the system is either not removing enough heat or losing the cold air it makes. Start with the filter, the thermostat, and the outdoor unit, then move to refrigerant, duct leaks, and sizing, which need a pro.
An AC that never shuts off but never gets the house comfortable is one of the most frustrating calls we get in Stillwater. The system is working hard, the electric bill is climbing, and the rooms are still warm. Usually the AC is not broken in an obvious way. It is either struggling to reject heat, low on refrigerant, or losing cold air through the ducts before it ever reaches you.
Run through the simple checks first. A dirty filter or a thermostat set too low for the equipment to keep up can both cause this. If those are fine, the problem is deeper, and running the system day and night to chase the temperature can wear out the compressor. Better to find the cause than to keep pushing.
It is worth knowing the limit of any air conditioner. On a 100 degree Oklahoma day, a healthy AC can only lower the indoor air so far below the outdoor temperature. Asking it to hold 68 degrees when it is 104 outside is more than most systems can deliver, and that is not a repair, it is physics. The checks below help you tell the difference between a system that is at its limit and one that is actually failing.
Check these first
Check the thermostat. If it is set very low on a 100 degree day, the AC may simply be running at full capacity and cannot reach the setpoint. Try raising it a few degrees and see if the system cycles normally. A reasonable setpoint in extreme heat is 72 to 76 degrees.
Safe to check yourselfSwap the air filter. A dirty filter cuts airflow and cooling output, so the system runs longer to do less. A clean filter is the cheapest thing to try first, and it is the cause more often than people expect.
Safe to check yourselfLook at the outdoor condenser. Is the coil clogged with dirt or cottonwood? Is the fan spinning? A dirty outdoor coil cannot reject heat, so the system runs all day and the house stays warm. Clear debris and give the unit room to breathe.
Safe to check yourselfCheck your vents and returns. Closed or blocked returns choke the system and cut cooling. Make sure nothing is covering the big return grilles, since a blocked return starves the whole system of air.
Safe to check yourselfLow refrigerant. If the system is clean and airflow is good but the air is only mildly cool, the charge may be low from a leak. Refrigerant work needs a licensed technician to find and seal the leak and weigh in the right charge.
Needs a licensed proDuct leaks or an undersized system. Leaky ducts in the attic can dump cold air where you cannot feel it, and an undersized AC will run all day in extreme heat and never catch up. Both need a pro to measure and fix.
Needs a licensed proDo not keep lowering the thermostat to force it. An AC can only drop the indoor temperature so many degrees below the outdoor temperature, and pushing it harder just runs up the bill and wears out the equipment. If the system runs all day and the house will not cool, call (405) 338-9194 before the compressor pays the price.
Call (405) 338-9194Going deeper
On the hottest Oklahoma days, even a healthy AC may run a long time to hold temperature. The line between normal and a problem is whether the house ever reaches the setpoint and whether the air at the vents feels cool. If the vents blow lukewarm and the system never cycles off, something is cutting its capacity.
The usual suspects are a dirty outdoor coil that cannot reject heat, a low refrigerant charge that cannot absorb heat, or leaky ducts that lose the cold air in the attic. An undersized system is the rarer case, and it usually shows up the first brutal summer, not suddenly years later. We measure airflow, duct leakage, and refrigerant charge to find which one it is instead of guessing.
Duct leakage is the sneaky one. In older homes around Stillwater and Cushing, the ducts in the attic can have gaps at every joint, and a big share of your cold air never makes it to the rooms. You pay to cool the attic while the house stays warm. Sealing the worst leaks often improves comfort and lowers bills more than any single repair, and we measure before and after so you can see the difference.
Watch a tech walk through it
Common questions
The system is either not removing enough heat or losing the cold air it makes. Common causes are a dirty filter, a clogged outdoor coil, low refrigerant, or leaky ducts. Check the filter and outdoor unit first.
Long run times are normal in extreme heat, but the house should still reach the setpoint and the vents should feel cool. If the vents blow lukewarm and it never cycles off, something is wrong.
It is possible, but a sudden change usually points to a repair issue like low refrigerant or a dirty coil, not sizing. We measure to tell the difference before recommending replacement.
Yes. Leaky ducts in the attic can lose a large share of your cold air before it reaches the rooms. We measure duct leakage to confirm and seal the worst leaks.
No. Pushing the thermostat lower runs up the bill and wears out the equipment. If the house will not cool, call (405) 338-9194 so we can find the real cause.
Call (405) 338-9194 any time, day or night. A real person answers and we get a licensed technician moving across Stillwater and the towns around it.
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