Shut off power and water, drain the line and the pan, clean out scale, close the vent inside, and cover the cabinet. Here is the full order, what each step prevents, and when to have it done for you.
Power off, water off, drain the line and pan, clean, close the damper, cover the unit. Do it before the first overnight freeze.
Most winter damage comes from water that was never drained: a split supply line, a rusted pan, or scale that dried hard. Ten minutes of draining in the fall prevents most of it, and closing the vent keeps heat in the house all winter.
Work only in dry, calm weather. If the cooler is on the roof, use a secured ladder and skip roof work entirely in wind, frost, or ice.
Turn the cooler off at the wall control, then cut power to the unit at the breaker, disconnect, or plug so the pump and motor cannot start while you work.
Close the water supply valve that feeds the cooler. It is often under a sink, in the attic, near the water heater, or where the small cooler line tees off a hose bib.
Drain the water line. Loosen the fitting at the cooler or open the drain point so the small copper or plastic line empties completely. Water left in the line is what splits it in a freeze.
Drain the reservoir pan. Pull the drain plug or overflow tube and let the water run off along the roof drain path, not onto shingles or a stucco wall.
Clean the pan while it is empty. Scoop out sediment, scrape loose mineral scale, and wipe it down. A diluted white vinegar solution softens light scale. Let the pan dry before closing the cooler.
Look over the pads. Aspen pads that are crusted, sagging, or smell musty are usually replaced each season. Rigid media can last several seasons if it is intact. Many people replace pads in spring instead.
Unplug the pump and set it in the dry pan or store it indoors. Note the belt condition and any rust spots so they can be handled at spring startup.
Close the cooler damper or cover the ceiling vent from inside the house. An open cooler duct lets warm air escape all winter and pulls cold air into the home.
Put a breathable cooler cover on the outside of the cabinet and strap it down so wind cannot lift it. A cover keeps out dust, leaves, snow, and nesting birds.
Water trapped in the supply line or fitting can freeze, crack the line, and leak the next time the water is turned on.
An uncovered vent and open damper can let heated air escape through the cooler all winter.
Standing water in the pan speeds up rust, and scale left to dry hard is harder to clean in spring.
Leaves, dust, and birds can collect inside an uncovered cabinet and clog pads and pump screens.
A winterizing visit is also a good time to have the pump, belt, motor, and pan checked so the cooler is ready when the heat comes back.
The cooler is roof-mounted and you are not comfortable on a ladder or roof You cannot find or close the water supply valve The water line, valve, or fitting is already leaking or cracked The pan is rusted through or the cabinet has holes You want the unit checked so it is ready for spring startup 
Your ZIP code and nearest city Where the cooler is mounted: roof, side wall, window, or ground Whether the water line is copper or plastic and where the shutoff is Any leaks, rust, or damage you noticed this season Whether you want winterizing only or a spring startup visit too The cooler brand and model if the label is visible Higher-elevation and northern service areas see overnight freezes in fall, so draining the line matters most there. Low-desert cities can usually wait until the cooling season ends.
In Denver, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in DenverIn Colorado Springs, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in Colorado SpringsIn Pueblo, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in PuebloIn Reno, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in RenoIn Salt Lake City, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in Salt Lake CityIn Prescott, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in PrescottIn Albuquerque, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in AlbuquerqueIn Loveland, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in LovelandIn Greeley, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in GreeleyIn Boise, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in BoiseIn Ogden, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in OgdenIn Provo, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in ProvoIn Orem, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in OremIn Sandy, drain the water line and pan before the first hard freeze, then close the vent for the heating season.
Swamp cooler service in Sandy
Get help when your cooler blows warm air, leaks, makes noise, or will not turn on.
Clean, inspect, and tune up your cooler before heat, scale, or worn parts cause a breakdown.
Replace worn or mineral-clogged pads so your cooler can move more air and cool better.
Shut it down before the first overnight freeze. In higher-elevation cities such as Denver, Colorado Springs, Reno, Salt Lake City, Prescott, and Albuquerque that is often in October. In the low desert, freezes are rare, but most people still drain and cover the cooler once the cooling season ends.
Yes. Drain both the reservoir pan and the water supply line. Standing water causes rust and scale, and water in the line can freeze and split it.
Covering the outside with a breathable, correctly sized cover helps keep out dust, debris, snow, and birds. Also close the damper or cover the ceiling vent inside so heated air does not escape through the duct.
You can leave pads in place if they are dry and intact, but crusted or musty pads are easier to replace now or at spring startup. Do not leave wet pads in a closed cabinet.
Many owners do, especially for window or ground units. Roof-mounted coolers involve ladder and roof work, so it is reasonable to have a technician handle the shutdown and check the unit at the same time.
Winterizing is usually priced like a seasonal service visit. A broad planning range for a seasonal tune-up is about $80 to $200, depending on access, cleaning needed, and whether parts are replaced.
If the cooler is on the roof or the line is already leaking, call or request an estimate and have the shutdown done in one visit.
