MasterCool Swamp Coolers: A Reno Owner's Reference

MasterCool is the rigid media line from Essick Air Products and Champion Cooler Corporation, and it is one of the brands you will find most often on a Reno roof when the cooler is newer than about fifteen years. This page is the reference: model naming, what the parts are actually called, and what fails first on Truckee Meadows water. Prices for any of the work are on the pricing page.

The model naming, decoded

MasterCool residential coolers are single-inlet units built in three discharge directions, and the model prefix tells you which: ASA is side discharge, ADA is down discharge, and AUA is up discharge for concealed ground-level installs. After the prefix comes the size and the media depth. A 51 is the smaller cabinet, a 71 is the larger, and a 12 suffix means 12 inch media instead of 8 inch. So an ADA5112 is a down-draft 51-size cabinet with 12 inch media.

The manufacturer’s coverage figures run from 1,370 to 5,024 CFM across the residential line. Its published table is worth knowing because it is honest about static pressure: an ASA71 with a 3/4 horsepower motor delivers 3,619 CFM at 0.1 inches of static, but only 2,978 at 0.5 inches. Ductwork is why the same cooler cools a single-story Sparks ranch and fails to cool a two-story Spanish Springs house.

Motors and pulleys ship separately on the standard line: 1/3, 1/2, 3/4, and 1 horsepower options with pulleys of 3-1/2 by 1/2, 4 by 1/2, or 4 by 5/8 inch bore. Belts are 57 inch on the 51 cabinets and 67 inch on the 71 cabinets. The Contractor Line (AS1C for 115 volt, AS2C for 230 volt) arrives fully assembled with motor, pump, pulley, purge system, and thermostat, and the two-speed motors on those are what most installs actually get. In Reno, where the July normal low is 60.4 against a normal high of 93.9, that two-speed motor and thermostat are the parts you will use every evening; the too-cold-at-night page explains why.

What is inside, in the right words

Naming the part correctly is half of getting the right one on the truck. MasterCool’s own component list covers:

• Water distribution system: PVC tubing and a protective housing that spreads water across the top of the media. The parts catalog sells the water distributor tube, the distributor housing, and a distributor filter pad separately. A clogged distributor is a classic “wet at the top, dry at the bottom” complaint.
• Float: an adjustable brass float arm with a splash guard. Sold as a float valve assembly.
• Pump: a thermally protected, UL recognized submersible pump, with a pump basket, retainer, screen, and receptacle as separate parts.
• Purge pump: an optional kit with its own bracket. MasterCool markets it as reducing mineral build-up and extending media life.
• Media: Munters CELdek rigid media, certified to UL Greenguard standards, with a five year limited warranty.
• Wet section and reservoir: a non-corrosive thermoplastic reservoir with a limited lifetime warranty, plus a non-metallic moisture shield that keeps water off the steel cabinet.
• Cabinet and blower: galvanized steel with a polyester powder coat, bolted rather than welded construction, a machine-balanced blower wheel, and a mesh prefilter screen.

Why the purge system matters in Reno

Rigid media pads are stacked corrugated sheets. MasterCool’s own description of the benefit is that air passes through at a lower velocity, which raises saturation and produces cooler air. On the same physics, the media holds more water for longer, and it sheds mineral scale better than shredded aspen does when the pan is bled or purged properly.

That matters here because of how Reno’s water behaves across a season. The Truckee Meadows Water Authority’s river water is soft, 2 to 5 grains per gallon in most of Reno and Sparks by its own area reports, but the same reports swing by area and by quarter rather than holding steady: Southwest Reno read 13.9 grains in the first quarter of 2026 and 2.6 in the second, West Reno 10.4 and then 6.7. TMWA says the groundwater wells it runs from mid-April through October can and do change the water chemistry somewhat. A cooler that sees 3 grains one quarter and 14 the next needs a purge system more than one that sees a steady number, because the pan concentration climbs fast whenever the supply turns hard. Scale is what seizes pumps, sticks floats, and turns pads into a crust that air blows straight through, which is the most common warm air call of the summer.

On rebates, the honest note: unlike the Colorado and New Mexico utilities, we could not find an NV Energy rebate for evaporative coolers, so the choice between 8 inch and 12 inch media is a comfort-and-lifespan decision here, not a rebate-tier decision. The permits and licensing page explains what we looked at.

What fails, in order

1. Pump. Scale on the impeller, or a dry-run burnout after the float stuck. $150 to $400 installed. Check the pump screen first; a packed screen looks exactly like a dead pump. The pump-not-pumping page has the two-minute test.
2. Float valve assembly. Sticks closed and starves the pads, or sticks open and sends water over the roof edge. $100 to $250. This is the leaking water call.
3. Belt. 57 or 67 inch depending on cabinet. $40 to $100 with the visit, and the cheapest fix on the roof.
4. Distribution tubing and filter pad. Cheap parts, easy to miss, and the reason a pad wets unevenly.
5. Media. Three to five years, sooner without a working purge. Rigid media runs $300 to $700 a set against $80 to $200 for aspen.
6. Motor. $300 to $700, two-speed at the top of the range. Check the capacitor and the blower bearings before condemning one.

The good news on this line is the pan. MasterCool’s reservoir is thermoplastic with a limited lifetime warranty, which sidesteps the rust-through failure that ends the life of a lot of older galvanized coolers on the 1950s Sparks ranches. It also means a MasterCool left full into Reno’s October freeze cracks a pump housing rather than splitting a pan seam, which is a cheaper mistake, though the fall winterization is still the right answer. If your pan is sound, almost every repair on the pump and float page is worth doing.

For the aspen side of the same family, see the Champion and Essick page. For the other rigid media line common in the West, see the AeroCool page. For what a repair costs on your unit, the repair cost calculator uses the published ranges.