The Ultimate Guide to Evaporative Cooler Maintenance & Repair

DIY Swamp Cooler Service, Troubleshooting & Replacement Parts

If you own a residential evaporative cooler (swamp cooler), regular maintenance is not optional. Because of hard water, dust, and mineral buildup, evaporative coolers are high-maintenance systems. The good news? Almost everything can be serviced by a homeowner with basic tools.
This comprehensive DIY evaporative cooler maintenance and troubleshooting guide will help you:
• Start up your cooler properly each season
• Clean mineral buildup and prevent corrosion
• Replace cooling pads and pumps
• Adjust belts and lubricate bearings
• Troubleshoot airflow, water leaks, and electrical problems
• Extend the life of your swamp cooler
For replacement parts and tools, visit: Indoor Comfort Supply

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⚠️ Safety First Before Working on Your Evaporative Cooler

Before servicing any evaporative cooler:
✔ Turn off power at the breaker and indoor control switch
✔ Never work on a cooler with standing water and live electricity
✔ Use caution on ladders and rooftops
✔ Stay hydrated and avoid overheating in the sun
Water in the pan and supply tubing increases the risk of electrical shock
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Seasonal Start-Up Checklist for Evaporative Coolers

Every spring, follow this process to prepare your swamp cooler for the cooling season.
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1. Remove Covers & Dampers

• Remove and store the winter cooler cover
• Remove slide or “cookie sheet” dampers
• Leave barometric dampers installed, they open automatically when running
Shop Cooler Covers
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2. Remove Cooling Pads

For Standard Aspen Pad Coolers
• Remove pad frames carefully
• Lay flat but don’t let them slide off the roof

For Mastercool or Rigid Media Coolers
• Remove front louver grille
• Remove wet section top panel
• Remove water distributor tube assembly
• Remove rigid media pad blocks
Tip: Rigid media pads often appear as one piece but are usually multiple blocks stuck together by minerals. You may need firm pressure to separate them. Try not to damage reusable pads
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3. Deep Clean Mineral & Mud Buildup

Because of hard water, calcium deposits build up quickly and can destroy metal components

Clean the Water Pan
• Remove any mud, mold, algae and dirt that may be present
• Use a garden hose, sponge, rags, or wet-vac
• Scrape white mineral buildup using a wire brush and metal scraper
• Be careful not to chip the paint
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4. Clean the Water Distribution System

Mineral buildup clogs pumps and distribution tubes.
• Remove pump and clean basket/screen
• Spray WD40 on pump shaft and impeller and ensure it spins freely
• Flush distribution tubes with a hose and cleaning cable
Shop Evaporative Cooler Pumps
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5. Protect the Metal

After cleaning:
• Coat the water pan with a sealer (submarine sealer recommended) to extend life
• Paint bare metal areas with rust-resistant paint
• Allow sealer to dry completely before refilling with water
Shop Cooler Maintenance Tools & Supplies
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Cooling Pad Maintenance & Replacement

Aspen Pads

Replace yearly for best cooling performance
• Remove retainer wires and old pads
• Clean out mineral build up, dirt and debris
• Use enamel paint on retainer wires to prolong usability or replace if necessary
• Install new aspen pads

Shop Aspen Cooler Pads
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Rigid Media (Mastercool Style) Pads

Rigid media pads can often be cleaned and reused for several seasons

How to Clean Rigid Media Pads:
1. Lay flat with mineralized side up
2. Use wide paint scraper or putty knife
3. Scrape firmly without gouging channels
4. Flush with garden hose while scraping
5. Use descaling solution if needed

Replace pads if:
• They no longer absorb water properly
• Mineral buildup cannot be removed
• Pads feel extremely heavy
Shop Rigid Media Pads
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Float Valve & Water Level Adjustment

The float valve should shut off when water is ½"–¾" below the overflow pipe.
If it does not shut off completely, replace it.
Shop Float Valves
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Bleed-Off & Water Quality Control

Evaporative coolers must remove mineral-rich water.
Options:
✔ Install bleed-off tube from pump to drain
✔ Install a Clean Machine purge system
Bleed-off may use 1–2 gallons per hour
Clean Machine dumps calcified water every 6 hours and refills with fresh water
This dramatically reduces calcium buildup and extends pad life.
Shop Bleed Off and Purge Kits
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Blower Belt Inspection & Adjustment

Check belt every season.
Replace if cracked or worn
Proper tension:
✔ ¾ inch of play when pressed with fingers
✔ Too tight damages motor and blower bearings
✔ Too loose reduces airflow
Shop Cooler Belts
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Blower Bearings & Motor Maintenance

Oil the Bearings
• Lift oil cup cap
• Use zoom spout oiler
• Spin blower to check for smooth operation
If squeaking continues, bearings may need replacement
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Replacing Blower Bearings

If bearings make scraping or squeaking noises and blower doesn’t spin freely, they must be replaced
This may require:
• Cutting rusted bolts
• Removing blower pulley
• Cutting seized bearings off shaft
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Blower Shaft or Blower Replacement

More advanced repair:
• Remove bearings
• Loosen blower collars
• Cut blower spokes if shaft is seized
• Remove housing if needed
When reinstalling:
Ensure blower is installed in correct airflow direction
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Electrical Wiring & Controls

Most evaporative coolers have simple wiring:
• White wires connect to common
• Red wire typically low speed
• Black or white/blue stripe is high speed
• Small black wire powers pump

6 Position Switch Wiring
• Bottom screw: hot 115V
• Left top: high speed
• Center: pump
• Right: low speed
Always disconnect power before working on wiring
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Troubleshooting Common Evaporative Cooler Problems

Not Cooling Well

• Pads clogged or dry
• Pump not circulating water
• No bleed-off installed
• Mineral buildup restricting airflow
Solution:
Clean pads, clean pump, install bleed-off system
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Weak Airflow

• Loose belt
• Worn bearings
• Blower installed backwards
• Obstructed duct
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Water Leaking

• Float valve not shutting off
• Cracked pan
• Drain clogged
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Strange Noises

• Worn bearings
• Loose pulley
• Motor squeaking
Spray WD40 through rear motor vents if switch squeaks
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Why Regular Maintenance Matters

Because of hard water and dusty air, evaporative coolers can develop:
• 1–2 inches of mud in pan
• Heavy calcium buildup
• Rust and corrosion
• Pump failure
• Reduced cooling efficiency
Annual service prevents expensive repairs and can save hundreds of dollars in service calls
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Shop Evaporative Cooler Parts & Supplies

Find Everything You Need at Indoor Comfort Supply
Evaporative Cooler Pads
Mastercool Rigid Media Pads
Water Pumps & Purge Systems
Float Valves
Belts & Pulleys
Bearings & Motors
Cooler Covers
Cleaning Tools & Sealers
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Final Thoughts

With proper evaporative cooler maintenance, including cleaning mineral buildup, replacing cooling pads, adjusting belts, and protecting metal surfaces, your swamp cooler can provide reliable, energy-efficient cooling for many years.