When a Denver heat wave hits, there’s nothing more frustrating than realizing your air conditioner isn’t working. Before scheduling emergency AC repair, there are a few simple troubleshooting steps that could save you time — and possibly money.
If your AC is not cooling your Littleton or South Denver Metro home, here’s what to check first.
1. Check the Power Supply
Start with the basics. If your air conditioner won’t turn on, it may not be receiving power.
- Check your home’s electrical panel for a tripped breaker.
- Reset it once and see if the system restarts.
- If it trips again, stop there — that’s usually a sign of a larger electrical issue that requires professional repair.
2. Inspect the Thermostat Settings
It sounds simple, but thermostat settings are one of the most common causes of AC issues.
- Make sure it’s set to “Cool.”
- Set the temperature at least 5 degrees below the current room temperature.
- Replace batteries if the display is blank or unresponsive.
A faulty thermostat can mimic a much bigger AC problem.
3. Replace Dirty Air Filters
Clogged air filters restrict airflow and can cause your system to shut down or stop cooling effectively.
- Remove and inspect your filter.
- If it’s dirty, replace it immediately.
- Change filters every 1–3 months, especially during peak summer use in the Denver Metro area.
Restricted airflow can also cause your system to freeze up.
4. Check for Ice on the Unit
If your AC isn’t cooling properly, look for ice buildup on the indoor coil or refrigerant lines.
If you see ice:
- Turn the system off.
- Switch the fan to “On” to help thaw it.
- Replace the filter if needed.
If icing continues, it could indicate low refrigerant or airflow problems that require professional service.
5. Clear the Outdoor Condenser Unit
Your outdoor unit needs proper airflow to function.
- Remove leaves, grass clippings, and debris.
- Trim plants back at least 2 feet.
- Make sure nothing is blocking airflow around the unit.
Overheating outdoor units are a common cause of AC breakdowns during Colorado heat waves.
6. Inspect the Condensate Drain Line
A clogged condensate line can cause your AC to shut down completely.
- Look for standing water near the indoor unit.
- Check the drain pan for overflow.
If you suspect a blockage and aren’t comfortable clearing it, this is a good time to call for service.
When to Call for Emergency AC Repair
If you notice any of the following, skip the DIY troubleshooting and call a professional:
- Breaker keeps tripping
- Burning smells
- Loud banging or grinding noises
- Warm air blowing continuously
- Complete system failure during extreme heat
These signs often indicate mechanical or electrical issues that require immediate attention.
Frequently Asked Questions
Why is my AC running but not cooling?
Common causes include dirty filters, thermostat issues, frozen coils, or low refrigerant levels.
How often should I service my air conditioner?
Annual maintenance before summer helps prevent emergency breakdowns.
Why does my AC keep turning on and off?
Short cycling can result from airflow issues, thermostat problems, or an oversized system.
For over 50 years, Southwest Heating & Cooling has been the trusted choice for homeowners across Littleton, Highlands Ranch, Centennial, Castle Rock, Lakewood, Englewood, Parker, and South Denver (service areas). Call Southwest Heating & Cooling today at 303-791-2679 or schedule a service and experience comfort you can count on. You won’t find better service anywhere else.