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Why is my swamp cooler blowing warm air?

A swamp cooler blows warm air when water is not reaching the pads, when scale has crusted the pads so air passes without picking up moisture, or when the outside air is too humid for evaporation to cool anything. A cooler is a simple machine: warm dry air in, water evaporated into it, cooler air out. Every warm-air failure is one of those three links broken.

Water is not reaching the pads

Lift the side panel and look before anything else. If the pads are bone dry with the pump running, the water supply is off, the float valve failed closed, the pump is dead, or the spider distribution tubes on top are clogged. A dry cooler in June is usually a supply valve or a pump, both ordinary parts replacement repairs. If the pan is full and the pads are wet, skip to the next section.

Scale-caked pads

Phoenix tap water is hard enough to crust pads with white mineral scale within a season or two. Scaled pads stop wicking water and stop evaporating; the blower pushes air through what is basically a dry sponge. The tell is visible crust on the pad surface and weak cooling that gets worse as the afternoon climbs. Scale lives in the pan too; a cooler with heavy scale usually needs the pads and a pan cleaning in the same visit, or the new pads crust right back.

It is July and the air is wet

The honest physics: an evaporative cooler only cools as much as the air is dry. When monsoon moisture pushes dew points up, typically mid-July through August, a perfectly healthy cooler puts out air barely ten degrees below outside temperature. That is not a failure, and no repair changes it. Houses that need real cooling in those weeks either pair the cooler with a window unit in the bedrooms or look at a cooler-to-AC conversion.

Everything else, a stuck damper, a clogged bleed-off, a pump limping, is a cooler repair visit in the typical few-hundreds range for the metro, confirmed and priced by the company that does the work. Tell the desk whether the pads are wet or dry on the request form; that one fact decides what kind of visit gets scheduled.