MasterCool Swamp Coolers: A Pueblo Owner's Reference

MasterCool is the rigid media line from Essick Air Products and Champion Cooler Corporation, and it is one of the two brands you will find most often on a Pueblo 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 Arkansas Valley 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 Belmont ranch and fails to cool a two-story Pueblo West 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 Pueblo installs actually get.

What is inside, in the right words

Naming the part correctly is half of getting the right one to the roof. 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 rigid media matters more in Pueblo than in most places

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 Pueblo Water publishes a total hardness averaging 180 mg/L, or 10.5 grains per gallon, calling it hard to very hard, with the plant reading 240 mg/L (14.0 grains) at one point this year. Homes on well water east of the city see more. Scale is what seizes pumps, sticks floats, and turns pads into a mineral crust that air blows straight through, which is the most common warm air call of the summer.

There is also a money reason. Black Hills Energy’s 2026 rebate tiers pay $150 for any qualifying cooler over 2,500 CFM, but $450 and $1,200 require media saturation of 85 percent or better, and the $1,200 tier additionally requires periodic purge water control and a remote thermostat. Aspen does not reach 85 percent. Twelve inch rigid media does. The rebates and permits page has the full table and the San Isabel alternative.

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.
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 overflow 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 bleed-off or 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 in this city. If your pan is sound, almost every repair on the parts page is worth doing.

For the aspen side of the same family, plus the AeroCool line from Phoenix Manufacturing, see the Champion, Essick and AeroCool page. To price a repair on your own MasterCool, run it through the repair cost calculator, which works from our published ranges.