How to Winterize Your Swamp Cooler in the Phoenix Area

Winterizing a swamp cooler means shutting it down properly for the months you won't use it. You turn off the power and the water supply, drain and clean the water pan, and put a cover over the unit. If the cooler is centrally ducted, meaning it blows its air through your home's ductwork, you also close its dampers. A cooler mounted in a window is different, and the Department of Energy's guide to evaporative coolers says to remove it completely and store it elsewhere so the window can be shut for the winter.

A swamp cooler, also called an evaporative cooler, cools your home by pulling outdoor air through thick pads that a pump keeps soaked with water. As air moves through the wet pads, some of that water evaporates and the air cools down before a blower fan pushes it into the house. Because the cooler holds water and sits outdoors all year, it needs a real shutdown when the season ends. The same guide recommends servicing a cooler at least twice a year, once at spring start-up and once at winter shutdown.

When Should You Shut Down Your Swamp Cooler?

The right time is after you've stopped using the cooler for the season and before you start running your heater. There's no single calendar date that works for every home. The order does matter in one way, and it comes down to the dampers.

On a ducted cooler, the damper closes off the duct between the cooler and your home, and closing it is part of the winter shutdown. If you turn on your furnace or heat pump while that damper is still open, the duct leaves an opening between your heated living space and the cooler outside.

Some homes also have ceiling exhaust vents, which usually let air out of the house into the attic while the cooler runs. The dampers on those vents should be closed during the heating season.

There are four practical reasons to shut the cooler down instead of switching it off:

• Mineral deposits. A good winterizing includes removing mineral deposits, especially around the fan, the water spray nozzles and the tray.
• Standing water. DOE warns that standing water left in the pan can become a breeding ground for mosquitos and bacteria. It says to empty the pan whenever the cooler will sit idle for more than a few days during the cooling season, and to drain and clean it in winter.
• Dust. A winter cover keeps dirt and dust from getting inside the unit.
• Heat loss. On a ducted cooler, an open damper leaves an opening between your heated living space and the cooler outside.

Key Takeaway: Shut your cooler down once you're done using it for the year and before you start heating your home. Close the dampers on a centrally ducted cooler as part of that shutdown, and keep any ceiling exhaust vent dampers closed during the heating season.

Step One: Turn Off the Power and Disconnect the Water

Start with the electricity. Make sure the power is off before any maintenance. For a long shutdown, unplug the motor and pump inside the cooler, as Champion's owner's manual directs. The pump moves water from the pan up to the pads, and the motor drives the blower fan, so unplugging both means nothing can switch on while the cooler sits dry.

Next, shut off the water line for the winter. At the end of the season, drain all the water out of the cooler and the supply line. Then keep the line disconnected from both the unit and the water supply so it does not freeze. In practice, you close the shutoff valve that feeds the cooler, disconnect the small supply line at both ends, and let it drain empty. When our technicians winterize a cooler, we also blow out the water supply line.

If you can't find the valve that feeds your cooler, or the line won't come loose without force, stop there and have a technician take a look. If your cooler sits on the roof, think honestly about whether you're comfortable working up there. Every step in this guide can wait for a professional visit, and none of them is worth a risky climb.

Drain and Clean the Water Pan

The pan is the tray at the bottom of the cooler that holds the water the pump sends up to the pads. At winter shutdown, the pan should be drained and cleaned. DOE's winterizing instructions are specific: "Winterize the cooler by draining and drying completely and removing mineral deposits, especially at jointed or moving parts associated with the fan, the water spray nozzles, and the tray."

Mineral deposits, often called scale, are buildup from the minerals in the cooler's water. Scrub the pan and tray until the crust is gone, then let everything dry fully before you close the cooler up. Check that the spray nozzles are aimed to soak the pads, and clean them with vinegar to remove calcification. Calcification is another word for that mineral crust.

Some coolers have a bleed-off line, which drains off some of the water to reduce mineral concentrations. That helps prevent scale buildup, and Champion's manual recommends a bleed-off kit "to increase the life of the cooler." If your cooler has a bleed-off line, make sure it's empty and clear at shutdown. If it doesn't have one, that's worth asking about before next summer.

Standing water is the other reason to be thorough. During the cooling season, DOE says the pan should be emptied whenever the cooler will be idle for more than a few days. That's because standing water left in the pan "can become a breeding ground for mosquitos and bacteria." A winter shutdown is a much longer idle period, and a dry pan gives neither one a place to start.

Key Takeaway: A dry, clean pan is the core of a good shutdown. Drain every bit of water, dry the pan completely, and scrub the mineral buildup off the tray, the spray nozzles and the parts around the fan.

What About the Pads, Pump, Float and Belt?

While the cooler is open, take a few minutes to look over its working parts. You don't need to replace much in the fall. The goal is to know what will need attention in spring so nothing catches you by surprise.

Pads. Torn, worn or mildewed pads should be replaced. Pad changes belong on the spring start-up list, and at the beginning of the season a clean pad is more absorbent and delivers more cool air. For that reason, it usually makes sense to inspect the pads now and put fresh ones in when the cooling season starts.

Pump. Cleaning the pump is necessary once a year at start-up, so that job belongs on the spring list. At shutdown, unplug the motor and pump as described above. If you notice the pump has been clogging or running noisily, make a note of it for spring.

Float. The float is the part the cooler's water line attaches to. Make sure the float operates properly, and check that it moves freely and isn't crusted with scale.

Belt and bearing. On coolers with a belt-driven blower, our technicians remove the blower belt and oil the bearing as part of the winter shutdown. Note the belt's condition when it comes off. When it goes back on in the spring, the belt should be inspected for proper tension.

Cover the Cooler and Close the Damper

These two steps close the cooler up for the winter. DOE's winterizing instructions say to "cover the entire unit with a plastic or canvas cover and close dampers if the unit is centrally ducted." A winter cover keeps dirt and dust from getting inside the unit, and it also helps protect the life of the finish on the cabinet. Choose a cover made for your cooler's size.

If your home has ceiling exhaust vents, they need attention too. These vents typically let air out of the house into the attic while the cooler runs. They usually come with a barometric damper, which opens on its own when the cooler is on. Some have a mechanically controlled damper, which needs electricity and control wiring to operate.

Either type of damper should be closed during the heating season. If your home has these vents, check that their dampers are closed before you start heating.

Key Takeaway: Cover the whole cooler to keep dust out and protect its finish, close its dampers if it is centrally ducted, and make sure any ceiling exhaust vent dampers are closed before you start heating your home. If your cooler is mounted in a window, remove it and store it elsewhere for the winter.

What Spring Start-Up Will Look Like

When warm weather returns, you'll reverse the winter steps by removing the cover and reconnecting the water line. Then you'll handle the start-up tasks from the Champion owner's manual and DOE's guide:

• Clean the pump, which is necessary once a year at start-up.
• Replace or clean the pads.
• Put the blower belt back on if it was removed at shutdown, then check its tension and adjust it if needed.
• Oil the blower bearings once a year, and the motor too if it has oil lines, using the oil type your manual names. If the bearings were oiled at shutdown, they don't need it again at start-up. Champion's manual also warns, "Do not over oil."
• Make sure the bleed-off valve isn't clogged.
• Clean the cabinet and inspect it for damage.

For a closer look at in-season care and common repairs, see our guide to swamp cooler maintenance and repairs in Gilbert.

Key Takeaway: Spring start-up covers the pump, the pads, the belt, oiling if it wasn't done at shutdown, the bleed-off valve and the cabinet, so the notes you make during your fall shutdown help you know what to have ready.

Should You Winterize It Yourself or Call a Pro?

If your cooler is easy to reach, you may be able to handle the shutdown yourself. The steps are straightforward: power off, water off, drain and clean, look over the parts, cover the unit and close any dampers. Keep your cooler's owner's manual handy, because models differ and the manufacturer's instructions for your unit come first.

A professional visit makes sense when the cooler is on the roof, when the water line or valve is stuck or leaking, or when you'd rather have someone check the pump, float, belt and dampers at the same time. Viking Heating & Air Conditioning is a family-owned HVAC company in Chandler. We service swamp coolers for homeowners across the Phoenix East Valley.

Since this is the same time of year you'll switch over to heating, it's also a good moment to look at the rest of your system. Our guide on how to prepare your HVAC system for colder weather in the Phoenix Valley covers the heating side of the seasonal changeover.

Frequently Asked Questions

Do I need to winterize a swamp cooler in the Phoenix area?

Yes. A cooler that sits unused for the cool months still holds water and collects dust, and a centrally ducted cooler stays connected to your ductwork. The Department of Energy recommends servicing a cooler at least twice a year, once at spring start-up and once at winter shutdown. A proper shutdown keeps standing water and mineral deposits out of the pan and keeps dust out of the unit. On a centrally ducted cooler, it also closes the dampers before you start heating your home.

When should I shut down my swamp cooler for the season?

Shut it down once you have stopped using it for cooling and before you start running your heat. There is no single date that fits every home. If your cooler is centrally ducted, closing its dampers is part of the shutdown, so finish before heating season begins.

How do I drain a swamp cooler?

Turn off the power first, then close the valve that feeds the cooler's water line. Champion's owner's manual says to drain all of the water out of the cooler and the water supply line at the end of the season. It also says to keep the line disconnected from both the unit and the water supply. When our technicians winterize a cooler, we also blow out the supply line. After that, empty the pan, let it dry completely and clean off mineral deposits, especially around the fan parts, the spray nozzles and the tray.

Should I cover my swamp cooler in the winter?

Yes. A winter cover keeps dirt and dust from getting inside the unit, and the Department of Energy recommends covering the entire cooler with a plastic or canvas cover. A cover also helps protect the life of the cabinet's finish during long periods when the cooler is not in use. Choose a cover made for your unit's size. If your cooler is mounted in a window, the Department of Energy says to remove it completely and store it elsewhere for the winter.

Should I replace swamp cooler pads before winter?

In most cases it makes more sense to inspect the pads now and replace them at spring start-up. The Champion manual lists pad changes as a spring start-up task and notes that a clean pad is more absorbent and delivers more cool air. If you find torn, worn or mildewed pads during your fall shutdown, write it down so new pads are ready when cooling season starts.

Why does the swamp cooler damper need to be closed in winter?

On a centrally ducted cooler, the damper closes off the duct that connects the cooler to your home. The Department of Energy's winterizing checklist says to close dampers if the unit is centrally ducted. When the damper stays open, the duct leaves an opening between your living space and the cooler outside. The Department of Energy also says the dampers on ceiling exhaust vents should be closed during the heating season. Close those before you turn on the heat too.

Does Viking HVAC service swamp coolers?

Yes. We service swamp coolers for homeowners across the Phoenix East Valley. If your cooler sits on the roof, or you would rather not handle the water line and electrical steps yourself, give us a call at (480) 689-5167.

Getting Your Cooler Ready for Winter

A good swamp cooler shutdown takes a few steps and a little time. Turn off the power and unplug the motor and pump, shut off and disconnect the water line, drain and dry the pan, and scrub away mineral buildup. Then look over the pads, pump, float and belt, and cover the unit. Before you start heating the house, close the dampers on a centrally ducted cooler, plus any ceiling exhaust vent dampers. Doing this in the fall keeps standing water and dust out of the cooler over the winter.

Can't tell whether your cooler is ducted or which dampers your home has? We're happy to help, especially if your cooler sits on the roof. Call us at (480) 689-5167 or send us a message through our contact page.