If your AC unit doesn’t come on, there are a number of things that could be wrong. Sometimes, with a little luck you can quickly and easily determine the cause – and perhaps even correct this annoying problem yourself.
Here are 4 common reasons your AC unit won’t come on – along with some details about what to do to get your house cool again:
Make sure the thermostat is set correctly before you call for help or check anything else. Maybe you looked at it too early in the morning and got confused. Maybe your spouse or a child turned it off. Or maybe it’s malfunctioning. There could be a power issue causing the thermostat to not work, and some units need fresh batteries frequently. Make sure yours is working, is set to cool and is set at least 3 degrees below the current room temperature. If there’s no obvious problem with the thermostat, it’s time to look for other causes.
The reason your AC unit doesn’t come on could be as simple as a tripped breaker. This can be due to a power surge from the electric company or from someone overpowering the circuit, but don’t just turn it back on and forget it. Stay close and make sure it doesn’t turn back off quickly. If it does, you need an HVAC technician to assess your system because there’s probably a mechanical problem. Remember that to properly reset a circuit breaker, you must first turn it all the way off before you try to turn it on.
Indoor AC units have a drain pan under them meant to accumulate condensation that doesn’t drain from the unit. This drain pan may have a float switch that will cause the unit to turn off if it’s triggered. And that’s a good thing – because the pan would run over and do damage if it wasn’t there. Remove the water from the pan to get the unit working again, but look for clogged drain hoses or other causes to prevent it from happening again. You should also have your HVAC system professionally serviced as soon as possible to make sure the drain stays clear.
No matter the cause of your AC unit not coming on, an HVAC technician can diagnose the reason and get your system working again so that everyone in your household is comfortable again. So check a couple of things yourself, then if nothing works, depend on the experts to get your system working right.
Help! My AC Unit Won't Come On
When your AC unit won't come on at all, the cause is usually electrical or a safety shutoff. Here is what to check and when to call a professional.
Why Your AC Won't Turn On
- Thermostat is off, set wrong, or has dead batteries
- Tripped circuit breaker or blown fuse
- The outdoor disconnect switch is off
- A failed capacitor or contactor
- A full drain pan tripping the float safety switch
- A tripped condensate or safety switch
What to Do Next
Check your thermostat, breaker, and disconnect switch first. If the unit still will not start, the problem is likely electrical and needs a technician. See our air conditioning repair services or schedule service, or call (972) 288-2263 for same-day help.
AC Won't Turn On FAQ
Why won't my AC unit come on?
Common causes include a thermostat problem, a tripped breaker or blown fuse, an off disconnect switch, a failed capacitor, or a tripped safety or float switch.
What should I check first if my AC won't turn on?
Check that the thermostat is on and set to cool with fresh batteries, then confirm the circuit breaker and outdoor disconnect switch are on.
Why does my AC breaker keep tripping?
A repeatedly tripping breaker usually signals an electrical fault, short, or overheating component and should be diagnosed by a technician.
Can a clogged drain stop my AC from turning on?
Yes. A full drain pan can trip the float safety switch, which shuts the system off to prevent water damage.
Can Xtreme Air Services fix an AC that won't start?
Yes. Our technicians diagnose and repair AC startup and electrical issues across Dallas-Fort Worth, often the same day.
