It’s hot, humid and the last thing you want to deal with is a broken AC.
Your AC may not turn on for the following reasons:
- Outlet isn’t functional
- Faulty circuit breakers
- AC is set to “Auto”
- Your air conditioner needs to be reset
- Clogged AC drain line
- Air filter is dirty
- Refrigerant is leaking
- Air conditioner motor failure
- Thermostat is broken
- Fan is damaged
- Drain pan is clogged
Before you call an HVAC technician to come and fix your AC, check out the 11 reasons below to troubleshoot why your AC won’t turn on.
Let’s get started.
11 Reasons Why Your AC Won’t Turn On
1. Make sure that the outlet is functional
This may sound like a no-brainer, but you would be surprised how easy it is miss. Check if the outlet your air conditioner is plugged into is functioning properly.
You can plug something else into the socket to see if the socket is the issue.
Try plugging something else into the same outlet to see if it does the same thing.
2. Check Circuit Breakers
For whatever reason, your circuit breaker may have tripped while you weren’t at home.
Two places you can check to see if this is the culprit:
Disconnect box
Sometimes an air conditioner unit will have a shut-off box right next to it. In that shutoff box, there will be fuses.
If there is a blown fuse, your air conditioner will stop operating. Never replace a blown fuse without shutting off the power first.
Never attempt messing withAT a fuse box if you don’t feel comfortable; leave the risky parts to an HVAC technician to get the job done safely.
Electrical panel
Go to your main electrical panel and see if there is a tripped circuit breaker.
Most older homes have a fuse box, but if you have an electrical panel, simply move the circuit back to the “on” position and see if that fixes your air conditioner.
3. Make sure your ac is set to “On”
If you turn your air conditioner on “Auto”, it may not operate unless it senses the temperature has dropped below your set temperature.
Turn your thermostat to “On” so that your air conditioner continuously operates.
4. Maybe it just needs a reboot
Like all electrical equipment, sometimes they just need to be restarted.
Depending on the type of air conditioner unit you have, you may have to restart yours., some will have a “restart” button. If yours does, all you need to do is push that button.
If you don’t have a restart button, go to your thermostat and shut off your ac that way. Wait about five minutes and then turn it back on.
If your air conditioner won’t turn on after the restart or if it does but doesn’t stay on, you will need to contact an HVAC technician to diagnose the issue.
5. Clogged AC drain line
If you don’t keep up with the maintenance of your air conditioning system, it may get clogged with gunk and back up, causing your AC to not turn on.
You can keep your condensation drain line clean if you pour a cup of boiling water down your drain pipe. You should do this every 30 days.
However, always be sure you shut the power off to your air conditioner and power supply before doing so.
You can learn more about unclogging your AC drain line here.
6. Dirty air filter
For an HVAC system like an air conditioner to run properly, you need to maintain the air filter.
A clogged air filter means it has debris and dust built up. When this happens, the airflow will be restricted and the coils will freeze.
When coils freeze up, the AC will not cool your home or won’t turn on at all if there is ice present.
Before you check to see if you have ice buildup, make sure your air conditioner is set to “off” even if it’s not turning on.
Use the shut-off switch to all the breakers that supply power.
Once all the power is off, you can replace the clogged air filter. However, if there was ice buildup, you will have to wait a while for all of the ice to defrost.
You can’t turn your AC unit on before it’s finished defrosting or you will damage the AC.
If you need to start up your AC sooner, you can use a blow dryer on the lowest setting to help speed up the coil defrosting process.
7. Refrigerant Leak
If you notice your air conditioner is not producing the quality of cool air like it used to, your electric bills are rising for no reason, or hear a hissing noise, these are all signs you could have a refrigerant leak.
A refrigerant leak is a serious problem because if it’s left unresolved, it could cause refrigerant poisoning if exposed for too long.
If you find that a refrigerant leak is why your AC isn’t turning on, it’s best to leave it to an HVAC technician to take care of it safely.
8. Air conditioner motor failure
A capacitor is a part that your ac unit’s motor. When an air conditioner is older than 15-20 years, it’s more likely that you’ll experience a faulty capacitor.
Over time, heat can cause your capacitor to wear out and die of old age.
You should never diagnose a capacitor yourself as it can carry a charge. Always rely on a professional technician to do electric work.
9. Thermostat malfunctioning
When your thermostat malfunctions, it can impact the performance of your air conditioner.
You can do this by first checking if the display on your thermostat is lit up. When it’s off, it won’t signal your air conditioner to turn back on.
Next, check the batteries of the thermostat if it is battery operated.
If the batteries are fine, you can check the settings; make sure it is set to “cool” and change it to a few degrees under the indoor temperature.
If this still isn’t doing the trick, turn the thermostat completely off, take off the cover, and check the inside components.
Check for any corrosion or debris buildup. See if there are any blown fuses.
If you want, you can clean out the debris yourself with a soft-bristled brush. However, if you have corrosion issues, be sure to contact an HVAC technician.
10. Fan issue
If you can’t figure out why your air conditioner stopped working, check the fan on the unit. If the fan isn’t working, you may have a dormancy issue.
If you have an outside ac cooling system that lays dormant in the wintertime, it could have stopped rotating if there was dirt buildup.
11. Drain pan clogged
The drain pan collects the moisture and is located under the evaporator coils inside the unit.
Once it collects the moisture, it flows into the condensation drain line and gets directed outside.
If you don’t keep up with the maintenance of the drain pan, it can become clogged.
Once it gets too clogged, it will reach the float switch and shut the unit off. It’s a safety switch and mechanism that prevents your AC from turning on to avoid damage.
You can use a wet/dry vacuum to get all of the blockages out, but it can get quite messy. Your best bet is to call an experienced HVAC professional.
When to Call an HVAC Professional?
When your air conditioner doesn’t turn on, it can be overwhelming with all the potential causes. If you don’t want to try and figure it out on your own, you can contact an HVAC professional right away.
You can try to resolve any of the issues above you feel comfortable with on your own. The first place to start would be to make sure there are no outlet issues and that the air filter is clean.
It may also be too cold for your AC to run. If your AC is running super loud, check out our guide to fix that issue once it turns back on.
