When the AC Quits at 105°F: What to Do Before Anyone Arrives
Updated 2026-10 · Modesto, CA
People before the equipment
A Modesto house with no cooling on a 105°F afternoon can pass 90 inside within a few hours. Babies, older people, anyone pregnant, anyone on medication that affects heat tolerance, and pets are at risk first. If any of them are in the house, move them somewhere cool now rather than waiting on a repair: a relative's house, a cool public building, or one of the cooling zones Stanislaus County lists each year at stanemergency.com (check hours first). Signs of heat illness such as confusion, a very high temperature or stopping sweating are a 911 call.
The checks worth doing
- Thermostat on cool, set below room temperature, batteries fresh
- Breakers for both the indoor unit and the outdoor unit (there are usually two); reset each once
- The outdoor disconnect, a grey box on the wall near the unit, switched on or its pull-out fitted
- The filter: a clogged one can freeze the coil and stop the cooling
- The overflow pan under the attic or closet unit: water in it can trip a float switch that shuts the AC off
What not to do
Do not keep resetting a breaker that trips. Do not run the system with ice on the copper line or the indoor coil; turn cooling off and run the fan alone to thaw it. Do not spray the outdoor unit with a pressure washer, and do not open its electrical panel. A capacitor holds a charge even with the power off.
And do not leave the thermostat calling for cooling on a system that is clearly not cooling. If the compressor is struggling without its fan, or without enough refrigerant, every extra hour risks turning a capacitor repair into a compressor replacement.
What to tell the company
Whether the outdoor fan spins. Whether the outdoor unit hums or is silent. Whether air comes out of the vents at all, and whether it is cool, room temperature or warm. Whether there is ice anywhere. The system's age. That description lets a technician bring the right parts on the first trip, which matters on the days everyone in Modesto is calling at once.
AC out now? Call and describe what you see. A local heating and air company will tell you when they can get there.
Making the house hold out
Close blinds and curtains on the west and south sides by early afternoon. Keep the oven off. Run ceiling fans counter-clockwise. Open the house up after sunset if the outdoor air drops below the indoor; Modesto nights in a heat wave often fall into the 60s or low 70s, and that cool air is worth letting in until morning, unless smoke is in the air.
Next year
Most heat-wave failures are parts that were already weak in April: a capacitor reading low, a coil packed with harvest dust, a condensate line half-blocked. A March or April tune-up, when searches for AC repair in Modesto sit at a fraction of their May peak, finds most of them.
Where to go next
Common questions
Why does my outdoor unit hum but the fan does not spin?
Most often a failed capacitor. Turn the system off so the compressor is not running without its fan, and call.
Is it normal for the AC to run constantly at 105°F?
Fairly normal for a correctly sized system on the hottest afternoons. It should still hold the house within a reasonable margin and catch up after sunset.
Can I add refrigerant myself?
No. Refrigerant work requires EPA certification, and low refrigerant means a leak that needs finding.