Swamp Coolers, Refrigerated Air, and Your Ducts: A New Mexico Guide

How a direct evaporative cooler moves air

EIA defines an evaporative cooler as equipment that uses the evaporation of water to cool air, and notes it is commonly found in warm, dry climates. New Mexico's technical resource manual for utility energy-efficiency programs describes the residential version as a direct evaporative cooler used in place of a refrigerated split-system air conditioner: warm, dry outside air is turned into cool, moist air that goes directly indoors.

Much of New Mexico is the kind of warm, dry climate EIA associates with these coolers. On the energy-code climate map, the southern and central counties are classified hot-dry or mixed-dry, both defined by less than 20 inches of precipitation a year.

Sources: U.S. EIA — RECS terminology; New Mexico Public Regulation Commission — New Mexico Technical Resource Manual for the Calculation of Energy Efficiency Savings, 2025–2026; PNNL / U.S. DOE Building America — Guide to Determining Climate Zones by County (PNNL-33270, 2022)

What comes in with the outside air

New Mexico's technical manual notes that evaporative coolers supply a continuous stream of fresh air and add moisture, which can help in low-humidity regions. The flip side is that outdoor conditions come in too. For wildfire smoke, EPA suggests covering a cooler's outside air intakes with high-efficiency (MERV 13) filters if they can be reached safely; otherwise, it advises using the cooler sparingly during smoky conditions because it can bring more smoke inside.

Dust on grilles isn't automatically a duct problem. EPA says it is normal for return registers to get dusty and that this doesn't indicate the ducts are contaminated with heavy deposits of dust or debris.

Sources: New Mexico Public Regulation Commission — New Mexico Technical Resource Manual for the Calculation of Energy Efficiency Savings, 2025–2026; U.S. EPA — Wildfires and Indoor Air Quality; U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

One duct system or two? Questions to answer first

In EIA's 2020 survey, about 67% of New Mexico homes heated mainly with a furnace, which delivers warm air through ducts, while only about 53% used central air. That leaves plenty of homes where the cooling equipment and the heating ducts aren't the same system. Before scheduling a duct cleaning, it helps to know:

• Does the cooler feed its own duct, blow through a single central grille, or connect to the same ducts the furnace uses?
• Where do the ducts run — attic, crawlspace, under the floor, or through a finished ceiling?
• Are there separate returns for the furnace, or does the house rely on open windows or relief vents while the cooler runs?
• Is the problem heavy buildup inside the ducts, debris coming out of registers, or signs of pests — or mainly dust on the grilles?

Sources: U.S. EIA — Highlights for space heating in U.S. homes by state, 2020 (RECS); U.S. EIA — Highlights for air conditioning in U.S. homes by state, 2020 (RECS); U.S. EIA — RECS terminology

What duct cleaning covers, and what it doesn't

Our air duct cleaning removes accumulated dust and debris from the supply and return ducts, registers, and grilles we can reach. It doesn't include cooler maintenance — pads, pump, water line, float, or belt — and we don't apply biocides, sanitizers, or sealants, or diagnose or remediate mold.

EPA does not recommend routine duct cleaning. It suggests considering it when ducts are clogged with excessive dust and debris or particles come out of supply registers, when ducts are infested with vermin, or when there is substantial visible mold growth inside hard-surface ducts, and it says duct cleaning has never been shown to actually prevent health problems.

Source: U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?