Living room on a hot afternoon with sunlight through blinds, a ceiling fan and a wall thermostat

AC not cooling · Pueblo, CO

AC running, but the house won’t cool down

If the thermostat says 72 and the house says 82, something in the system is losing ground. Call us and a technician will find out what.

Call (719) 670-8043 What to check first

24/7 · Licensed & insured · Pueblo & Pueblo West

Answering calls 24/7
Licensed & insured technicians
Pueblo & Pueblo West, ZIPs 81001–81012

First: is the air coming out cold?

Hold your hand at a supply vent for a few seconds. The answer splits the problem in two.

The air is cool, but the house still won’t drop. The system is working, just not keeping up — usually an airflow, coil or capacity problem. Keep reading.
The air is room temperature or warm. The cooling side has stopped. That’s a different list of causes, covered on our warm-air page.

A Pueblo-specific note: on a 103-degree afternoon like the five the city saw in 2025, even a healthy system can run nonstop and still lag a few degrees behind the setting. The real test is whether it catches up after sunset. If it’s 9 p.m., the outside temperature is falling and the house still isn’t, call us.

Why an AC loses the race

Restricted airflow

The indoor coil needs a steady stream of house air across it. A clogged filter, closed or blocked return grilles, or a struggling blower motor cuts that stream. Cooling drops off, and if it gets bad enough the coil starts to freeze.

A dirty outdoor coil

The outdoor unit’s job is to dump the house’s heat outside. When its fins are packed with dust, grass clippings or debris, it can’t shed that heat — and in a Pueblo July it has very little margin to spare. Cleaning the outdoor coil is a standard part of an AC tune-up.

A refrigerant leak

Low refrigerant means a leak somewhere in the coils, the copper line set or a fitting. Cooling fades gradually, the indoor coil may ice up, and sometimes you can hear a hiss near the lines. Finding and repairing the leak is the fix; refilling without it isn’t.

Typical U.S. range for a refrigerant leak repair: $250–$1,500, per Angi, October 2026 — a national figure, not a Pueblo quote. Your exact price comes after diagnosis.

Outdoor fan or capacitor trouble

If the outdoor unit hums but its fan isn’t turning, a failed run capacitor or fan motor is the usual cause. Running in that state can ruin the compressor, so turn the system off and call.

Thermostat in the wrong spot

A thermostat in afternoon sun, or right next to a supply register, reads the wrong temperature and can shut the system off early. It’s a surprisingly common reason one room is fine while the rest of the house bakes.

What you can safely check

Replace a dirty filter. If it’s gray and matted, swap it, then give the system an hour.
Open every return grille. Move furniture, rugs or boxes that block the big grilles where air is drawn in.
Look at the outdoor unit. Clear away weeds, toys and stored items. Lennox recommends about two feet of open space around it. Is the fan on top spinning?
Close the blinds on the sunny side. West-facing rooms in a Pueblo afternoon pile on heat the system has to remove.

Don’t hose down or open the outdoor unit yourself while it’s powered, and never try to add refrigerant — that requires EPA certification and the right equipment.

Call now if…

you see frost or ice on the copper lines or indoor unit;
you hear hissing, grinding, banging or a loud buzz;
the outdoor fan won’t spin, or the breaker trips again after one reset;
it ran all night and the house is still warm in the morning.

Someone feeling sick from the heat? Health first, AC second.

If anyone in the house is elderly, ill, very young, or showing signs of heat illness, don’t wait on a repair. Get them somewhere cool now: an air-conditioned home of family or friends, or an air-conditioned public building.

Call 911 for signs of heat stroke: a body temperature of 103°F or higher; hot, red, dry or damp skin; a fast, strong pulse; confusion; or passing out. While you wait, move the person somewhere cooler and cool them with wet cloths or a cool bath. Don’t give them anything to drink.

Heavy sweating, cold and clammy skin, a fast but weak pulse, nausea, cramps or dizziness point to heat exhaustion. Move to a cool place, loosen clothing and sip water, and get medical help if they vomit, get worse, or aren’t better within an hour.

Questions we hear

It’s 100 degrees out. Is it normal for the AC to run all afternoon?

On Pueblo’s hottest afternoons, a working system may run for hours without shutting off — that alone isn’t a fault. The warning signs are a house that keeps getting warmer while it runs, air from the vents that isn’t noticeably cool, or a system that still hasn’t caught up by late evening once the outside temperature drops.

Can you just top off the refrigerant?

Refrigerant isn’t used up like fuel. If the system is low, it’s leaking somewhere, and adding more without finding the leak means paying for the same refrigerant again later. Our technicians check the charge, look for the leak, and explain the options — including what the refrigerant type in your system means for cost.

Should I turn the AC off until you get here?

If you see ice on the lines, hear hissing or grinding, or the outdoor fan isn’t spinning, yes — turn cooling off at the thermostat. Otherwise it’s usually fine to let it run while you wait, but tell us exactly what you’re seeing when you call.