AC Stopped Working in a Heat Wave? Do This Before You Call

There's a particular flavor of phone call we get during a West Michigan heat wave. It's about 4 p.m., the house has climbed past 82, and the voice on the line is somewhere between annoyed and worried. The AC was fine yesterday. Today it's doing nothing, and the forecast says three more days of this.

I'll tell you what I tell them. Before anything else, spend ten minutes on the checks below. A decent share of "dead" air conditioners come back to life without a service call, and even when they don't, what you find will make the repair visit faster.

Ten Minutes of Checks Before You Call

Work through these in order. None of them require tools or crawling around anything dangerous.

1. The thermostat. Confirm it's on COOL and set a few degrees below the current room temperature. If the screen is blank or unresponsive, try fresh batteries. It sounds too simple to be the answer, and yet dead thermostat batteries account for more summer no-cool calls than I'd care to admit. Our thermostat troubleshooting post covers this in more detail.

2. The breaker. Go to your electrical panel and look for a tripped breaker, usually labeled AC, condenser, or air handler. Reset it one time. If it holds, watch the system for the rest of the day. If it trips again, stop there and leave it off. A breaker that keeps tripping means something is pulling too much current, and repeatedly forcing it is how compressors get killed.

3. The filter. Pull it and hold it up to a light. If you can't see through it, the system may have been suffocating for weeks, and the heat wave finished the job. Put in a fresh one.

4. Ice. Look at the indoor unit and the copper lines running to it. Ice anywhere means the system froze, and it will not cool again until it fully thaws, which takes a few hours with the cooling off and the fan running. Ice also explains mystery water on the floor. We've covered both the frozen coil and the water leak versions of this story.

5. The outdoor unit. Make sure the fan is spinning when the system calls for cooling, and that the unit isn't wrapped in cottonwood fluff or hemmed in by overgrown shrubs. Check that nobody flipped the disconnect switch, the small box mounted on the wall next to the unit. It happens more than you'd think, especially after fence work or landscaping.

One more, if your system has it: a float switch in the condensate pan will shut the whole system down when the drain clogs. If the AC is silent and there's standing water in the pan by the furnace, that's your answer, and clearing the drain brings it back.

If None of That Worked

Then it's a repair call, and in a heat wave, so is half the county. Here's the honest version of how that goes: reputable shops run a triage list in hot weather, and no-cool calls go to the top of it. When you call, tell them what you already checked. "Breaker trips every time" or "the coil was frozen solid" points the technician at the problem before the van leaves the shop.

Be careful who you call in a panic. A heat wave brings out the same characters a hailstorm brings out for roofs. If someone quotes a full system replacement over the phone for a unit they've never seen, that's a red flag, not a diagnosis. We wrote a whole guide to hiring an HVAC contractor on spotting the difference.

Keeping the House Livable While You Wait

You can't make the house cold without the AC, but you can slow the climb, and you can keep the people in it safe.

Close the blinds on the south and west sides, keep the doors shut, and don't run the oven, the dishwasher, or the dryer until evening. Run fans in the rooms people occupy, and shut them off in empty rooms, since fans cool people rather than air. Once the outside temperature drops below the inside overnight, open windows on opposite sides of the house and let it flush. Our heat wave survival guide goes deeper on all of this.

Pick one room, ideally the coolest one, often the basement here in West Michigan, and make that the household headquarters instead of trying to defend the whole floor plan.

When It's a Real Emergency

For a healthy adult, a night in an 85-degree house is unpleasant. For an infant, an elderly parent, someone pregnant, or anyone with a heart or breathing condition, it's dangerous, and it deserves to be treated that way. Heat builds in a closed house, and indoor heat harms people every summer, mostly in exactly this situation: the AC failed and someone decided to tough it out.

If that describes your household, say so when you call, because it moves you up the list. And if the house is already hot, get the vulnerable person somewhere cool now rather than waiting on the repair: a relative's place, a library, anywhere with working air. The emergency page on our site covers how we handle after-hours cooling calls.

Why This Always Happens on the Worst Day

It isn't a conspiracy, though I understand why it feels like one. On the hottest days the system runs at maximum load for hours on end, and whatever part was quietly wearing out picks that moment to quit. The capacitor that limped through June dies on the Fourth of July, because the Fourth of July is when it finally got asked for everything it had.

That's the case for a spring AC tune-up, and I'll leave it at one sentence: weak capacitors, dirty coils, and loose connections all show themselves during a proper inspection, in April, when finding one is a footnote instead of a crisis.

We've been getting Grand Rapids area families through hot spells since 1987, and July is when we earn it. If your system is down and the checks above didn't bring it back, call us and we'll get you on the board for AC repair.