During a home inspection or a hot summer day, you might realize your AC is running but not cooling your home. You’re not alone—many California homeowners deal with this frustrating issue when they need their cooling system the most. If this happens, there could be several causes behind the problem.
This guide covers the most common reasons, how to troubleshoot them, and when to call a professional. Whether your AC isn’t cooling efficiently or has stopped working altogether, we’ve got you covered.
Why Your AC Is Running But Not Cooling: Top Causes
1. Dirty or Clogged Air Filter
A dirty filter restricts airflow, making it hard for your air conditioner to blow cold air.
- Symptoms: Weak airflow, warm air from vents
- Fix: Replace or clean your air filter every 1–3 months
2. Incorrect Thermostat Settings
Your thermostat might be set incorrectly or malfunctioning.
- Check: Is it set to “cool”? Is the temperature lower than the current room temp?
- Fix: Try adjusting the settings or replacing the thermostat
3. Low Refrigerant or Leak
If your AC unit is not blowing cold air, it might be low on refrigerant due to a leak.
- Signs: Ice on coils, hissing noise, higher energy bills
- Fix: Requires an HVAC pro to inspect, seal leaks, and recharge refrigerant
4. Frozen Evaporator Coils
Frozen coils prevent heat transfer, so your AC runs but doesn’t cool.
- Causes: Poor airflow or refrigerant issues
- Fix: Turn off the system to thaw coils, then call a technician to investigate
5. Dirty Outdoor Condenser Unit
A clogged or dirty condenser can’t release heat properly, reducing cooling.
- Fix: Turn off power and gently clean the unit with a hose, or schedule a pro cleaning
6. Faulty Fan or Compressor
If the outdoor unit’s fan or compressor isn’t working, your central air won’t cool the home.
- Fix: Call a licensed technician to diagnose and repair electrical or mechanical issues
AC Troubleshooting Checklist for Homeowners
Use this quick guide to narrow down the issue:
| Symptom | Likely Cause | Suggested Fix |
|---|---|---|
| AC running, but air feels warm | Dirty filter | Replace filter |
| Weak or no airflow | Frozen coils | Turn off AC, let thaw |
| Thermostat unresponsive | Batteries or unit failure | Replace batteries or thermostat |
| Outdoor unit runs, indoor unit doesn’t | Blower motor issue | Call HVAC technician |
| High energy bills | Low refrigerant or poor airflow | Schedule system inspection |
What If My Central AC Is Running But Not Blowing Air?
If your central air is running but not blowing air, the issue could be:
- A broken blower motor
- Electrical failure
- Clogged filters or ducts
These are signs that your AC system needs immediate professional attention.
Frequently Asked Questions
Why is my air conditioner not blowing cold air but running?
Common causes include dirty filters, frozen coils, low refrigerant, or thermostat issues. Start with a basic inspection and cleaning.
Why is my AC not working in the house?
If your AC is not cooling your house, check power sources, thermostat settings, and airflow. If nothing helps, it may be a refrigerant or electrical issue.
What should I do if my AC is not cooling?
- Replace the filter
- Reset or check thermostat settings
- Inspect for ice or leaks
- Call an HVAC technician for diagnosis
How often should AC units be serviced?
We recommend a full service at least once a year—preferably in early spring—before heavy summer use.
Final Thoughts
An AC that runs but doesn’t cool can be frustrating—but in many cases, the fix is simple. Start with easy steps like replacing the air filter or checking your thermostat. For more complex issues, don’t hesitate to call a HVAC contractor. To avoid problems in the future, schedule regular maintenance and have your system professionally inspected at least once a year.
Use our recommended partners at Airflow Heating & Air, Inc, (916) 607-9623, they help California homeowners get fast, reliable Air Conditioner diagnostics and repair.
✅ Licensed, insured, and trusted by thousands
🏡 Serving Sacramento, Elk Grove, Roseville, and nearby areas
🛠️ Transparent pricing & fast turnaround
