What to do when the AC quits in 110 degree heat
Call for service, check the breakers and filter, and move anyone at risk to an air-conditioned place. Don't count on the night to cool the house: in 2026 the airport recorded 27 nights that never dropped below 80°F.
On this page
Check these first
- Thermostat: set to cool, below room temperature, batteries good, screen on.
- Breakers: the air handler and the outdoor unit usually have separate breakers. Reset a tripped one once. If it trips again, leave it off.
- Filter: if it's clogged, replace it.
- Ice on the copper lines or indoor coil: set the system to off and the fan to on so it thaws. Running a frozen system can damage the compressor.
- Outdoor unit: is the fan turning? Is the unit humming without running? Either way, turn it off at the thermostat and wait for the technician.
Don't open the outdoor unit's electrical panel or try to push-start the fan with a stick. Capacitors hold a dangerous charge.
Keep people safe
The National Weather Service lists these signs of heat exhaustion:
- heavy sweating
- weakness or tiredness
- cool, pale, clammy skin
- a fast, weak pulse
- muscle cramps
- dizziness, nausea or vomiting
- headache
- fainting
Move the person somewhere cooler, preferably air-conditioned. Get medical help if they vomit or symptoms last more than an hour.
A body temperature above 103°F with hot, red skin can be heat stroke. Call 911. The NWS says not to give fluids to someone with heat stroke.
- The CDC says fans won't prevent heat illness when it's really hot, and even a few hours in air conditioning helps.
- The NWS says not to point a fan at yourself when the room is above 90°F, and to check on older and frail neighbors.
- Pima County runs cooling centers with a map on pima.gov. Its summer season runs May 15 to September 15.
Slow the heat gain while you wait
- Close blinds and curtains, especially on west and south windows.
- Shut doors to rooms you aren't using and stay in the coolest one.
- Skip the oven and the dryer.
How hot the house will get
Through October 24, 2026, 2026 had 77 days at 100°F or more at the airport and a high of 110°F on August 1, 2026. The record is 117°F, set June 26, 1990. A closed house without cooling heats up through the afternoon and holds it, so plan to leave rather than wait it out.
Average daily high and low by month, Tucson International Airport
Questions Tucson homeowners ask
Should I turn off my AC if it's not cooling?
If there's ice on the lines or coil, yes: set it to off with the fan on so it thaws. If the outdoor unit hums but won't start, turn it off and call. Running it can make the damage worse.
Can I call 911 if my AC is broken?
Call 911 for a medical emergency, such as signs of heat stroke. For the broken system, call an HVAC company. For a cool place to go, Pima County lists cooling centers on pima.gov.