Close the sunny side of the house
Pull blinds, shades, or curtains across sunny windows. Keep exterior doors and windows shut while the outdoor air's hotter than the air inside.
No-cooling guidance in Frederick, MD
How do you cool a house when it's 100 degrees outside?
Start with safe relief for the people in the home. Then separate a hard-working AC from one that's not cooling. What you feel at the vents and see at the outdoor unit points to the next step.
First moves
Make the house easier to cool while you decide.
Stop adding heat indoors
Use an outdoor grill instead of the oven when you can, run exhaust fans during cooking and showers, and move heat-producing electronics away from the thermostat.
Move air for comfort, not cooling
Ceiling, floor, and table fans can make a room feel better, but they don't remove heat. Turn them off in empty rooms, and don't lean on one as primary cooling in dangerous heat.
The U.S. Department of Energy's home cooling guidance explains how insulation, efficient windows and doors, shading, and air sealing reduce heat reaching the living space.
Read the symptom
A long run is different from a failed cooling system.
| What you notice | What to do next |
|---|---|
| The air's cool, but the house is slow to cool | Close blinds, cut indoor heat, keep doors shut, and check that supply registers and returns are open. |
| Air from the vents is warm | Confirm cooling mode and the setpoint, check the filter, then call us for an AC diagnosis if the air stays warm. |
| The outdoor unit's silent or a breaker trips | Don't keep resetting it. Leave electrical covers closed and let us handle the control and electrical testing. |
| You see water, ice, smoke, or an electrical odor | Turn the system off when it's safe. Treat smoke, sparking, and strong electrical odors as urgent safety conditions. |
Windows and fans
Open the windows only when the outdoor air helps.
If the air outside is hotter or more humid than the air inside, opening windows adds heat and moisture. Keep the house closed during peak afternoon heat. When outdoor air turns meaningfully cooler, a short stretch of natural ventilation can release built-up heat. Close the windows again before the next hot period.
A window fan can help in the right conditions. The Department of Energy's window-fan guidance describes exhausting hot air while bringing air in through a shaded window at the opposite end of the house. Windows near the exhaust fan should stay closed so the airflow follows that path.
Ceiling, floor, and table fans move air over people. They don't remove heat from the house. The CDC advises using fans indoors only when the temperature's below 90 degrees, because a fan can raise body temperature above that point.
What the equipment may be telling you
Persistent warm air can point to a thermostat problem, airflow restriction, a coil issue, or a refrigerant problem. Weak airflow can trace back to a dirty filter, a blower concern, or ductwork that's leaking, clogged, or constricted.
The Department of Energy lists dirty filters, thermostat issues, drainage problems, refrigerant problems, and electrical controls among common air-conditioner problem categories. Another thermostat adjustment won't confirm any of them.
Ice on the refrigerant line or indoor coil, water around the equipment, repeated on-and-off cycling, unusual electrical smells, or a system that won't start are good reasons to stop guessing and call us. Don't add refrigerant, bypass a safety control, open an electrical compartment, or try to repair a sealed system yourself.
If you call us for cooling service
We give the diagnosis a useful starting point.
- Describe the change: Share when the problem began, what the vents feel like, which rooms are affected, and what the outdoor unit does.
- Test the likely causes: We can check the thermostat's signal, the airflow and filter, the indoor coil, the drain, the controls, and the outdoor equipment.
- Explain the repair: You'll know the tested fault and repair scope before you approve the work.
- Check the result: We test the system for cooling, airflow, and safe operation against the original symptom.
People come first
Know when indoor heat is a health emergency.
If the home's turning dangerously hot, move children, older adults, people with chronic health conditions, pets, and anyone who feels unwell to a place with working air conditioning. The CDC recommends using air conditioning or finding a location that has it during extreme heat.
Don't wait for HVAC service if someone has:
- Confusion or loss of consciousness
- Seizures or signs of heat stroke
- Symptoms that are getting worse in the heat
Call 911, move the person to a cooler place, and follow emergency medical guidance. Ready.gov's extreme-heat guidance also advises finding a community cooling option if air conditioning isn't available.
Plan for the next hot day
If the house overheats every summer, look beyond the thermostat.
Window coverings, weather-stripping, air sealing, insulation, and attic conditions change how much heat enters the home. Properly designed attic ventilation may cut accumulated attic heat, but it doesn't replace safe indoor cooling during an extreme event.
Keep the filter on a regular check cycle, and book cooling maintenance with us before the hottest part of the season when you can. ENERGY STAR's maintenance checklist includes thermostat, electrical, moving-part, and drain checks in a professional visit.
If the home feels clammy even when the temperature looks acceptable, measure humidity instead of turning the thermostat down again and again. The EPA recommends indoor humidity between 30% and 50% when possible.
Answers for Frederick homeowners
Questions that come up next.
Should I set the thermostat much lower?
A very low setting doesn't make a failing system create more cooling. Use a reasonable target, keep the home shaded and closed, and pay attention to whether the air at the vents is actually cool.
Is it normal for the AC to run all day in extreme heat?
A working air conditioner may run for long stretches on a 100-degree day. Long run time alone doesn't prove a failure. Warm air, weak airflow, ice, water, a silent outdoor unit, or repeated breaker trips are more useful clues.
Should I open the windows or use a window fan?
Only when the outdoor air's meaningfully cooler and less humid than the indoor air. Keep windows closed during peak afternoon heat. If you use a window fan, set it to exhaust hot air from one area while bringing air in through a shaded opening at the opposite end.
What should I do if the house becomes dangerously hot?
Move children, older adults, people with chronic health conditions, pets, and anyone who feels unwell to a cooler place with working air conditioning. Call 911 for confusion, loss of consciousness, seizures, or other signs of heat stroke.
Make the home safer, then get the cooling fault named.
If the air conditioner's blowing warm air, airflow's weak, the system freezes, water appears, the outdoor unit won't start, or the home keeps getting hotter, tell us what changed and request a cooling diagnosis. If someone's in medical danger, call 911 first.