AC not keeping up on hot days in Pueblo: normal strain or a fault?

Why an AC falls behind on hot afternoons

An AC not keeping up on hot days is either a system working at its limit or a system with a fault. The house tells you which one. If it holds the set temperature on mild days and slips only in the afternoon heat, strain is likely. If it struggles on mild days too, a fault is more likely.

A few simple checks sort out most cases. They need only a thermostat, a filter and a look at the outdoor unit.

How hard should an AC work on a Pueblo summer afternoon?

If the checks below don't turn up the cause, the AC repair page explains what a contractor looks at.

The NOAA weather station near Pueblo records an average June to August daily high of 90.5°F. It also averages 74 days a year with a high of 90°F or more. An AC that runs through a stretch of those days is doing the job it was built for.

On the hottest afternoons, a healthy system may run for long stretches and let the house drift a degree or two above the setting. That is normal strain. The air at the vents should still feel clearly cool, and the outdoor fan should be spinning.

A fault looks different. Watch for these signs:

• Air from the vents feels warm or only barely cool.
• The system runs all day and never reaches the setting, even on a mild afternoon.
• Ice forms on the refrigerant lines or the indoor unit.
• The outdoor unit hums while its fan stays still.
• The system shuts off and restarts again and again, or the breaker trips.
• Water collects around the indoor unit.

A change from how the house behaved before tells you more than any single reading. If it held its temperature fine last summer and doesn't now, something has changed.

Which checks are safe to do yourself?

These checks are safe for any homeowner, and the order below saves the most effort.

1. Thermostat. Set it to cool with the fan on auto, a few degrees under the room reading. If the screen looks dim or flickers, put in fresh batteries.
2. Filter. Switch the system off, slide the filter out and hold it up to a light. If you can't see light through it, replace it with one of the same size. ENERGY STAR advises inspecting, cleaning or changing the filter in a central AC, furnace or heat pump once a month, and says a dirty filter can increase energy costs and damage equipment, and cause early failure.
3. Outdoor unit. Turn the power off at the disconnect or the breaker first. Then pull away leaves, cottonwood fluff, grass clippings and anything stacked against the cabinet. Trim plants back so air moves freely on every side, and don't pry at any panel.
4. Vents and returns. Look at each supply vent and return grille for rugs, drapes or furniture sitting in front of it.
5. Breaker. If the AC breaker has tripped, reset it one time. If it trips again, leave it off.

How do you know it worked? The air at the vents feels cool again, the outdoor fan spins, and the indoor temperature starts moving toward the setting. If none of that changes, stop checking and treat it as a fault. Opening the unit is not homeowner work.

What points to low refrigerant or a failing part?

Refrigerant is the fluid that carries heat out of the house through a sealed loop. It isn't used up like fuel, so a system that runs low has usually leaked somewhere.

Low refrigerant tends to show up as ice on the lines or indoor coil, a hissing or bubbling sound, or air that is only lukewarm while the outdoor fan runs. A failing part shows up in other ways. A worn run capacitor can leave the fan or compressor humming without starting. A dead fan motor leaves the outdoor unit silent. A struggling compressor often trips the breaker.

Leave the refrigerant loop, the wiring and the sealed parts to a licensed contractor, because the loop is pressurized and the wiring is live. The US Department of Energy says regular maintenance, such as charging refrigerant and replacing filters, is necessary to keep central air conditioners at peak performance. For a closer look at that process, read how a contractor diagnoses refrigerant, coils and electrical parts.

Age matters too. ENERGY STAR suggests considering replacement when an air conditioner is more than 10 years old. Note your unit's age from the label on the outdoor cabinet.

When should you switch the AC off?

Set the thermostat to off when you notice any of these:

• Ice on the refrigerant lines or the indoor unit.
• A breaker that trips again after you reset it.
• A burning or hot electrical smell.
• Water dripping or pooling at the indoor unit.
• Grinding, screeching or banging from either unit.

Then leave it off. Running the cooling with ice present asks the compressor to work against a blocked coil, and a burning smell or repeated trips can add risk.

A burning smell is not a gas smell. If you smell gas, leave the house, then call the gas utility from outside. If a carbon monoxide alarm sounds, get everyone out and call emergency services.

It helps to jot down what you saw: when the house falls behind, whether the outdoor fan runs, where ice or water appeared, and the unit's age. Waiting out a hot stretch with a known fault can turn a small repair into a larger one, because a struggling part keeps working against the rest of the system.

Calling about AC repair for a system that falls behind

If the checks didn't help, or a sign above told you to switch off, a licensed contractor can look at the refrigerant, wiring and sealed parts. The call goes to a phone line that connects callers with licensed, insured independent contractors. Where a contractor is available, the line connects your call to that contractor, and the contractor confirms availability and fees.

Details on repairs are on the AC repair in Pueblo page.