Shutting Down Your AC for the Season in Indiana

Last October, my buddy Dan in Carmel ignored his AC for two weeks after the leaves came down. By the time he pulled the outdoor disconnect, the top of his condenser looked like a raccoon's salad bowl—maple leaves, twigs, and one suspicious dryer sheet. He wrapped the whole thing in a blue tarp and forgot about it. April rolled around, and he called us out because the unit hummed but wouldn't cool. The tarp had trapped moisture against the coil, and a family of mice had turned the wiring harness into a nesting project. That's why I'm telling you this: a proper ac end of season shutdown isn't busy work. It's cheap insurance against a three-hundred-dollar repair or a three-week wait in spring.

When to Shut It Down (Not Too Early, Not Too Late)

Here in central Indiana, we get those false-fall weeks in late September where it's 80 on Monday and 55 on Wednesday. Don't rush to kill the AC on the first cool night. Wait until daytime highs stay below 65°F and most of the leaves have dropped—usually late October through early November. If you kill power too early, you'll get a random 70-degree day and curse yourself while sweating in the living room. If you wait too long, you risk a hard freeze with moisture still inside the unit, which is bad news for the coil. That window for an ac end of season shutdown is pretty forgiving, but don't push it past Thanksgiving.

Up in Zionsville and Westfield, oak leaves are thicker than a politician's promises. Down in Greenwood and Plainfield, maple helicopters clog the fins just as fast. So pay attention to your yard, not the calendar.

Start Inside: Thermostat First, Then Outdoor Power

First thing's first—go to the thermostat. Switch it from Cool to Heat if you're ready to use the furnace, or to Off if you're still coasting. Set the fan to Auto, not On. That lets the furnace manage its own airflow. If you're switching to heat now, you might want to check our fall furnace startup checklist before the cold snap. Then head outside. Find the small gray box attached to the wall next to the condenser. It's called the disconnect. Flip the handle down or pull the plug out—that kills power to the outdoor unit only. Your furnace and indoor blower stay powered, which is exactly what you want. If your disconnect is missing or looks sketchy, you can turn off the breaker labeled 'AC' or 'Condenser' in your main panel. Don't touch it if you're unsure. That's what we're here for.

Clean the Outdoor Unit: Leaves, Cottonwood, and Raccoon Salad

With the power off, get up close. Pull leaves, twigs, grass clippings, and whatever else out of the top and the fins. Use your hands (gloves help) or a soft brush. Keep two to three feet of clearance around the unit all winter. That means trimming back any shrubs or moving that pile of patio cushions you meant to store. Then, if the coil looks dirty, grab a hose with a regular nozzle. Spray from the inside out—that pushes dirt away from the fins, not deeper into them. Don't use a pressure washer. It bends the fins and makes things worse. Let the unit dry completely before you put any cover on top. Wet metal under a cover is a rust invitation. For a deeper dive on coil cleaning, check out our condenser cleaning guide.

Indoor Side: Three Quick Wins (Vinegar, Filter, Insulation)

Back inside, find the thin white PVC pipe dripping into a floor drain or small pump near the furnace. That's the condensate drain. Pour a cup of white vinegar down it. That kills the algae and gunk that would otherwise turn into a clog by spring. It stinks for a minute, but it works. That's a small step that's easy to skip, but it's part of a complete ac end of season shutdown. Next, check the air filter. If it's gray and furry, replace it. A clean filter helps your furnace run efficiently all winter. Not sure what MERV rating to use? We wrote a whole guide on that—check it out. Last, look at the two copper lines going into the outdoor unit. The larger one should be covered in black foam insulation. If that insulation is cracked or missing, especially on south- or west-facing walls, replace it before winter. It's cheap and easy.

To Cover or Not to Cover (And Why a Tarp Is a Bad Idea)

A lot of folks around Indianapolis wrap their AC like a Christmas present. That's a mistake. A full tarp traps moisture against the metal, invites rodents to nest, and can even cause mold on the coil. What you want is a top-only cover—either a breathable fabric version made for AC units or a piece of plywood with a brick on top to keep leaves and ice from falling into the fan. Leave the sides open so air can circulate. That's especially important under roof eaves where snow and ice chunks can slide off and dent the fan blades. In older neighborhoods like Broad Ripple and Irvington, many houses have low eaves right above the condenser. A top shield is non-negotiable there. Last winter, a guy in Avon didn't mark his condenser and his neighbor's snowplow took out the corner of the unit. A couple of orange stakes would have saved him eight hundred bucks. So mark your unit if it's anywhere near a driveway or sidewalk.

Heat Pumps? Different Story.

If you have a heat pump, stop right now. Do not shut off the power. A heat pump and a standard central AC look nearly identical from the outside. The difference is that a heat pump runs in winter to heat your home. If you cut its power, you'll have no heat. How do you know which you have? Look at your thermostat—if it has an 'Emergency Heat' or 'Aux Heat' setting, you likely have a heat pump. Or go outside and look at the unit's model number; a heat pump will have 'HP' somewhere. When in doubt, leave the power on and give us a call. We can tell you in five minutes.

When to Call HVACPros Instead of DIYing It

Some stuff isn't worth messing with. If you hear a loud buzzing or grinding from the outdoor unit when it was running last, don't just pull the disconnect and hope for the best. That's a sign of a failing capacitor or compressor. Oily stains on the refrigerant lines? That's a leak. Repeated icing during fall even when temps were mild? That's a refrigerant issue or airflow problem. And if your breaker trips every time the AC kicks on, something's shorted. These are the kinds of things that only get worse over winter. Better to have us look at it now than discover a dead compressor in May. We're local—we know the Indy weather and the way it beats up HVAC equipment. If you're hearing weird noises, our guide on HVAC noise diagnosis can help you figure out if it's serious.

Plan Ahead for Spring

One more thing: while you're doing all this, write down any cooling issues from this past summer—short cycling, weak airflow upstairs, that one weird smell in July. Then call us or go online and book a spring AC tune-up now. You'll get priority scheduling and a clear price before the busy season hits. When April comes, you won't be waiting three weeks for a tech while your house heats up. So here's the deal. You can do the basics yourself—thermostat, disconnect, vinegar, maybe a filter swap—in under an hour. But if you'd rather have a pro check the whole system before winter, or if you want to get on the spring tune-up calendar early, we'd love to help. We'll walk you through what we find and what it'll cost before we do anything. Head over to our quote page and tell us what you need.

Stay warm out there.