Problem guide
Air conditioner not working
Start by naming the symptom. Each one points to a different short list.
Get quotes Repair cost calculator
Written by HYRE HVAC Research Desk Primary-source research, data analysis and fact checking
The short answer
When an air conditioner is not working, sort it by symptom. Nothing turns on: check the thermostat, breakers, disconnect and float switch. Runs but blows warm air: check the thermostat mode, the filter and the outdoor unit.
Weak airflow or ice: change the filter and thaw the coil. Water around the indoor unit: the drain is likely clogged. Anything inside the outdoor unit or involving refrigerant needs a licensed technician.
Start with the symptom
| Symptom | Check first | Detailed guide |
|---|---|---|
| Nothing turns on | Thermostat, breakers, disconnect, float switch | AC not turning on |
| Runs, blows warm | Mode, setpoint, filter, outdoor fan | Fan not spinning |
| Weak airflow, ice on lines | Filter, thaw the coil | AC freezing up |
| Water around indoor unit | Drain line, pan | AC leaking water |
| Turns on and off quickly | Thermostat location, filter | Short cycling |
| Thermostat blank or flashing | Batteries, wait for delay | Thermostat not working |
Safe checks for any AC problem
Confirm the mode (cool or heat), the setpoint (below room temperature for cooling, above for heating), the fan setting and the batteries if it uses them.
Pull the filter. If you cannot see light through it, replace it. A clogged filter starves the system of airflow. ENERGY STAR suggests checking it monthly in heavy-use seasons.
If the breaker for the unit has tripped, switch it fully off, then on. If it trips again, leave it off: that is a fault for a technician, not something to keep resetting.
Remove debris and keep plants back. Do not open the panel.
Closed or blocked vents cut airflow and can freeze the coil.
Is it the AC or the heat outside?
On the hottest days, a correctly sized AC may run nonstop and still let the house drift a few degrees above the setpoint. That is normal at design conditions.
What is not normal: air from the vents that is barely cooler than the room, ice on the lines, or the outdoor unit silent while the indoor fan runs. Feel the large copper line at the outdoor unit while it runs; it should be cool. If it is warm, the system is not moving heat.
When to stop and call
Do not open the outdoor unit, furnace cabinet or control box. Capacitors can hold a dangerous charge with the power off, and line-voltage work is for a licensed technician.
Adding refrigerant, finding leaks or even attaching gauges requires EPA Section 608 certification.
Turn the system off at the breaker. If there is smoke or fire, leave and call 911.
Leave it off.
Is it an emergency?
Extreme heat can be dangerous, especially for older adults, infants, and people with health conditions. If someone feels unwell in the heat, move them somewhere cool and seek medical help. Our emergency checker helps decide how fast you need help, and emergency AC repair covers staying safe until it comes.
What a technician will check
A good diagnosis covers power and controls, the capacitor and contactor, both fans, the coils, airflow and refrigerant pressures, and the drain. It should be written down: what was tested, what failed. DOE’s 2018 review found refrigerant charge and airflow faults in most installed systems it studied, which is why measurements matter more than guesses.
HyreHVAC publishes no repair prices yet; use the repair cost calculator with your own quote.
Get connected
Tell us about the work
Three short steps: the job, your home, and how to reach you. Nothing goes to an HVAC company unless you agree.
A person reads it and replies, free and with no obligation. Matching is not live yet, so this is not a quote. If you smell gas or a CO alarm sounds, leave the house and call 911 or your gas utility first.
Get HVAC Options
A person at HyreHVAC reads the request and replies. Matching with contractors is not live yet, so this is not a quote.
Questions
Why is my air conditioner not cooling the house?
What should I check first when my AC stops working?
Can I fix my AC myself?
Why does my AC run but the house stays warm?
How hot is too hot inside?
Written and audited by
HYRE HVAC Research Desk
Primary-source research, data analysis and fact checking
We are a research desk, not a sales floor. We read the federal microdata file, the statute or the manufacturer data sheet ourselves, and we publish the figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify.
The counts below are generated from the published pages themselves, last counted October 26, 2026, and they are what we have actually published rather than what we intend to.
- 18
- studies published
- 15
- federal sources read and cited
- 15
- studies published with their full dataset as CSV
- 51
- jurisdictions reproduced against EIA’s own tables
How this desk works
- Primary sources only. Federal data comes from the agency that collects it, in the file that agency publishes. We do not cite an article that cites a source; we download the source and compute the figure ourselves.
- We validate against the agency before we publish. First, we use each federal microdata file to reproduce the agency’s own published tables. Our cooling research reproduces EIA’s state estimates and standard errors for all 51 jurisdictions. That check caught a variance formula that was off by a factor of four.
- Every estimate carries its uncertainty. These are survey figures, not counts. Standard errors are computed from the replicate weights the federal file supplies and printed beside the estimate. An estimate too imprecise to publish is reported as such rather than printed.
- Nothing is typed by hand. Prose, tables and charts all read from one dataset built by script, so a number in a sentence and the same number in the table below it cannot disagree.
- We publish the data, not just the conclusion. 15 of our 18 studies offer the full computed table as a CSV download on the page, so you can check the analysis or disagree with it. A study without a row-level dataset gets no download link and claims none in its structured data.
- We correct in public. Where we have published a figure wrongly we fix the figure, rewrite any analysis that rested on it rather than patching the number underneath it, and leave a dated correction note on the page.
- We do not install or sell HVAC equipment, and we take no payment for placement, ranking or a favorable mention. Nobody buys a position on this site.
Data as of Sources checked October 26, 2026. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
HyreHVAC is a publisher. We do not install, repair or inspect HVAC equipment and hold no contractor licence. Nothing here replaces an on-site diagnosis by a licensed contractor. Sources are cited with the date they were checked.