AC out in July: how to keep the house and the people in it safe until it is fixed

An unconditioned house in a DFW summer can reach the mid 90s inside by late afternoon and will not drop much overnight because the nights stay near 80. Heat illness in older adults and small children happens at temperatures that healthy adults find merely unpleasant. If someone in the house is in a vulnerable group, the plan is to get them somewhere cool today, not to wait and see. Collin County libraries and recreation centers serve as cooling spaces during the day, and a hotel night is cheaper than an emergency room.

These buy you several degrees, which matters when the repair is tomorrow morning.

• Close every blind and curtain, especially west-facing windows, before noon
• Run ceiling fans and box fans where people are; they do nothing in empty rooms
• Do not use the oven, the dryer or the dishwasher
• Sleep on the lowest floor; a two-story house can be ten degrees cooler downstairs
• Cold showers, wet cloths on the neck and wrists, and more water than feels necessary
• Do not open windows at night unless the outside air is actually cooler than the inside and the humidity is low, which in July it usually is not

Run the ten-minute check: thermostat, breakers, furnace switch, filter, float switch, outdoor fan, ice. Half of the time one of those is the answer. If the outdoor unit hums and the fan does not spin, it is almost certainly the capacitor, which a technician can replace in under an hour. If there is ice, turn the system off and the fan on so it is thawed when the technician arrives; a frozen coil cannot be diagnosed.

July is when the most systems are sold, and not all of them needed to be. A technician who arrives, looks at a 12-year-old system with a failed capacitor and recommends a $12,000 replacement without taking readings is selling. The right sequence is diagnose, quote the repair from a published price, and only then talk about age and efficiency. If the repair is a compressor or a coil on a system past 12 years, replacement may well be the right answer; it should still come with the repair number next to it. Our repair-or-replace rules are written for exactly this moment.

If the system is under ten years old, the failed part may be covered by the manufacturer's parts warranty, which is usually ten years when the original owner registered the equipment and five if not. Find the installation paperwork or the model and serial number from the data plate; a technician can check registration with the manufacturer. Labor is almost never covered, but a compressor under parts warranty turns a $3,000 repair into a few hundred.