Farmington’s first freeze doesn’t announce itself. NOAA climate data puts a 50 percent chance of hitting 32°F by October 13 and an 80 percent chance by October 22. That’s a narrower window than most homeowners expect, and it means a swamp cooler left running or simply switched off without a proper shutdown can be sitting in harm’s way before the month is out.
Flipping the power switch isn’t enough. Water still sitting in the pan, a feed line still connected to supply, and an open duct dumping cold air into the house: these are the conditions that cause cracked pans, seized pumps, and furnaces working overtime come November. We’ve been servicing evaporative coolers across the Farmington area for over 30 years, and our NATE-certified technicians handle this transition every fall for families who want it done right the first time.
Here’s what a proper shutdown actually involves.
Why Shutting Down Your Swamp Cooler Matters
Water expands when it freezes, and it doesn’t discriminate between your pan and your pump housing. If standing water remains in the cooler after temperatures drop, that expansion can crack cast metal pans, split the float valve body, and damage the pump housing beyond repair. Parts that could have lasted another season end up needing full replacement in spring.
There’s also a health angle most shutdown guides skip entirely. Stagnant water sitting in a warm pan through early October is an ideal environment for bacterial growth before temperatures finally drop. Emptying and cleaning the pan isn’t just about protecting the metal. It’s about not leaving a biohazard on your roof all winter.
Beyond the cooler itself, an uncovered duct opening is a direct cold-air pathway into your living space. That draft hits right as your furnace starts its first heating cycle of the season, forcing it to work harder than necessary from day one. Sealing that pathway is part of the shutdown, not an afterthought.
When to Shut It Down in Farmington
Mid-October is the target window. With a 50 percent freeze probability by October 13, half the years Farmington hits freezing temperatures before that date. Waiting until you feel the cold is waiting too long.
Draining the lines and pan while overnight temperatures are still safely above freezing is straightforward. Trying to drain lines that have already frozen shut is not. A frozen water supply line to the cooler creates a problem you can’t solve from the rooftop, and waiting for a thaw to finish the job costs time and risks damage in the meantime.
One thing worth knowing: swamp cooler shutdown and furnace startup are two halves of the same seasonal transition, not two separate projects. When we make a fall service visit, we handle both in one trip so your home moves from cooling season to heating season without a gap or a cold week in between.
The Step-by-Step Shutdown Process
A thorough shutdown covers the power, the water supply, the pan, the pads, and the duct. Skipping any one of them creates a problem that won’t show up until April.
Cutting Power & Water Supply
Start at the breaker or disconnect the unit at the plug. Then locate the water supply shutoff valve, typically on the line feeding up to the float valve inside the cooler, and close it fully. Disconnect the feed line from the cooler side so no water can reach the unit through the winter, even from a slow drip past a worn valve seat.
Draining & Cleaning the Pan
Remove the drain plug and let the pan empty completely. Once it’s drained, clean out the mineral scale and sediment before it dries and hardens. Farmington’s water is hard, and the mineral deposits left behind after a summer of evaporation can form a dense crust that accelerates rust and corrosion through the winter.
A vinegar soak breaks down light mineral buildup on the pump and float valve assembly; heavier scale may need a descaling solution. After cleaning, leave the drain plug out. Rain and snowmelt will find their way into the cooler no matter how good the cover is, and an open drain lets that water escape rather than collect.
Removing & Inspecting the Pads
Pull the evaporative cooler pads and inspect them. Pads saturated with mineral scale don’t cool efficiently and won’t improve over winter. If they’re heavily crusted, replace them in spring rather than reinstalling compromised material. For homeowners with Frigiking units, which we service as part of our evaporative cooling lineup, pad replacement specs vary by model, so it’s worth keeping the unit model handy when sourcing replacements.
Covering the Unit & Closing the Damper
A properly fitted cover tied down against wind keeps debris and moisture out of the housing. Don’t skip the tie-downs; a cover that blows off in a November windstorm isn’t doing anything. Inside the house, close the roof damper, the metal flap inside the duct that blocks airflow when the cooler isn’t running. An open damper leaves a direct pathway for cold outside air to pour into the duct system, which means your furnace is fighting a constant draft from the moment it fires up.
Common Shutdown Mistakes That Cause Spring Problems
Most spring startup headaches trace back to one of three errors made during the fall shutdown.
- Replacing the drain plug after cleaning. It feels like the tidy thing to do, but a closed drain traps any rain or snowmelt that gets past the cover. That water sits in the pan all winter and can still freeze and crack the metal, even with the supply line disconnected.
- Skipping the mineral descale. Mineral scale left on the pump impeller and float valve assembly hardens over winter. Come spring startup, those moving parts can seize or stick, turning a ten-minute startup into a repair call. A few minutes with a descaling solution in October can prevent that entirely.
- Forgetting the damper. This one shows up on your gas bill rather than your roof. An open duct during heating season is a steady energy drain, and it’s one of the easiest things to forget when the focus is on the cooler itself.
Pairing the Shutdown with Your Furnace Startup
The same ductwork that carried cool air all summer now needs to carry warm air efficiently. A damper left open, a duct seal compromised by a summer of operation, or a furnace filter that hasn’t been checked since spring all affect how well that first heating cycle performs. Seasonal HVAC maintenance treats the whole system as one, so nothing gets overlooked in the gap between cooling and heating seasons.
If you’d rather stay off the roof and know both systems are ready before the first freeze arrives, R.A. Biel Plumbing & Heating, Inc. handles fall evaporative cooler shutdowns and furnace startups together. Give us a call at (505) 278-5112 and we’ll get it scheduled before that mid-October window closes.