AC Won't Turn Off or Runs Constantly in Florida
AC running nonstop, or a fan that never shuts off? Liberty Air and Electric finds out if it's stuck on or just can't keep up.
- One check tells you which problem it is
- Same-day diagnostic, upfront quote
- Told straight when running all day is normal
Compare the Room Temperature to the Thermostat Setting First
Liberty Air and Electric diagnoses and repairs air conditioners that run without stopping, across Greater Orlando and South Florida. Most of the time when we get a call about an AC that won't turn off, the system isn't stuck.
One check sorts out most of it. Compare the room temperature on the thermostat with what it's set to.
If the room is warmer than the setting, the system is running because it hasn't gotten there yet. That's the one we see most.
If the room is at the setting and the system's still running, it's usually a variable-speed system working as designed, or a very hot day with a low setting.
If the room is colder than the setting and it's still cooling, it's stuck on. That's the only one we treat as a stuck system.
The house is warmer than the setting
The AC runs nonstop because it never gets the house down to the setting. That's the most common reason people call us about it, and the system isn't stuck.
The house is at the setting and a new variable-speed system keeps running
A variable-speed system runs most of the time at low speed. People who just had one put in often think something's wrong, and it's the second most common reason we get the call.
It's a very hot day and the setting is low
On a very hot day with the thermostat set low, running all day can be normal. It's holding the temperature you set.
Air keeps coming from the vents, but it isn't cold
The thermostat fan switch is set to ON, usually by accident. On ON, the indoor blower runs all the time, even when the system isn't cooling. So the air from the vents isn't cold between cycles, and the outdoor unit still shuts off like normal.
The house is colder than the setting and it won't stop
The system keeps cooling after the house drops below the setting. The cause is a low-voltage fault such as a shorted thermostat wire, and the house can get very cold.
Liberty Air and Electric tells you when running all day is normal
- One temperature check before you call
- Diagnostic fee waived with an approved repair
- Upfront pricing before any work starts
When the House Is Warmer Than the Setting, the AC Can't Keep Up
Liberty Air and Electric finds this more often than anything else on calls about an AC that won't turn off: the system never reaches the set temperature.
Several faults cause this, and they're the same ones behind an AC that isn't blowing cold air.
In most of these cases the air at the vents is still cool, just not cold enough to pull the house down to the setting. The usual ones are a refrigerant charge that's a little low or a little high, a dirty filter, a dirty coil, or a duct problem. Each one takes some cooling away without shutting the system down, so it keeps running.
When Running All Day Is Normal in Florida
Running all day is normal in two situations. You have a variable-speed system, or it's a very hot day and the thermostat is set low.
A variable-speed high-efficiency AC is built to run most of the time at low speed instead of cycling on and off at full speed. A lot of people who just had one installed don't expect that.
If the room is at the setting, nothing's wrong, and if it's above the setting, the system can't keep up. If the room is below the setting, it's stuck on.
Colder than the setting and it still won't stop?
Shut it off at both breakers and book a diagnostic. We find what's holding it on and quote the repair before any work starts.
When the AC Is Really Stuck On
Liberty Air and Electric sees two causes behind an AC that's truly stuck running. One is a fan switch set to ON, the other a low-voltage or parts fault. We see both less often than an AC that can't keep up or a new variable-speed system.
The fan switch is set to ON
Someone set the thermostat's fan switch to ON by accident. ON runs the indoor blower nonstop, and AUTO only runs it while the system is cooling. The cooling itself is fine.
You can tell by the air. It keeps blowing between cycles but it isn't cold, and the outdoor unit still shuts off.
Set the fan switch back to AUTO. You don't need us for that.
A contactor stuck closed
The contactor is a switch in the outdoor unit. A 24-volt signal from the thermostat closes it, and that runs the outdoor unit.
When a contactor sticks closed, the outdoor unit keeps running after the thermostat stops calling for cooling. With the fan on AUTO the indoor blower still shuts off, so the house doesn't get colder and you end up with a frozen coil instead.
In Florida a contactor replacement runs $150 to $400.
A shorted thermostat wire
Low-voltage wires carry the thermostat's signals to the equipment. A short in that wiring can hold the cooling signal on, so the system cools no matter what the thermostat is set to.
What happens next depends on which wire it shorts to. If the blower keeps running too, the house keeps getting colder than the setting. If only the outdoor unit runs, the coil ices over the same way it does with a stuck contactor.
Shut it off at both breakers
When the room is well below the setting and the house is too cold, go ahead and shut it off at the breakers. Turn off both, the one for the air handler and the one for the outdoor unit. Shut it off the same way if the outdoor unit keeps running with the thermostat set to OFF.
Turning the thermostat off won't stop a stuck contactor or a shorted wire. Once it's off at the breakers, book an AC repair diagnostic.
Questions?
Frequently Asked Questions About an AC That Won't Turn Off
Q: Why won't my AC turn off?
A: When an AC won't turn off, most of the time it hasn't reached the set temperature yet. Next most common is a variable-speed system running as designed. Less often it's actually stuck on, from a fan switch set to ON, a contactor stuck closed, or a shorted thermostat wire. Comparing the room temperature with the setting tells most of them apart, and a fan switch set to ON shows on the thermostat itself.
Q: Is it normal for an AC to run all day in Florida?
A: It can be normal for an AC to run all day in Florida. A variable-speed system is supposed to, and on a very hot day with a low setting it can be fine. It isn't normal if the house gets colder than the setting, or never gets down to the setting at all.
Q: Why does my AC fan keep running when the AC is off?
A: If your AC fan keeps running when the AC is off, the thermostat fan switch is most likely set to ON. ON runs the indoor blower all the time, cooling or not. Flip it to AUTO and the fan stops between cooling cycles. You can do that yourself. If the switch is already on AUTO and the fan still won't stop, that's a relay, wiring or thermostat fault, and it needs a diagnostic.
Q: Should the thermostat fan be set to ON or AUTO?
A: Set the thermostat fan to AUTO, not ON. With AUTO, the indoor blower only runs while the system is cooling. With ON, it never stops, so air keeps coming out of the vents between cycles, and that air isn't cold. If yours is on ON, you can switch it back to AUTO yourself without a visit.
Q: Why does my new variable-speed AC run all the time?
A: Your new variable-speed AC runs all the time because it's built to. It runs most of the time at low speed instead of cycling on and off at full speed. A lot of new owners think that means something's wrong. If the house is at the setting, it's fine.
Q: How do I shut off an AC that won't turn off?
A: To shut off an AC that won't turn off, use the breakers when the house is well below the setting and too cold. Turn off both, the air handler's and the outdoor unit's, then book a diagnostic. If the system ignores the thermostat, it has a low-voltage or parts fault.
Q: How much does it cost to fix an AC that won't turn off?
A: The cost to fix an AC that won't turn off starts with a diagnostic, which runs $49 to $149 in Florida depending on the season and day of the week. We waive that fee with an approved AC repair. Contactor replacement in Florida runs $150 to $400. A fan switch set to ON needs no repair.