How a swamp cooler actually cools
A swamp (evaporative) cooler works by pulling warm, dry Albuquerque air through pads that are kept wet by a small pump. As the water evaporates, it drops the air temperature before a blower pushes it into your home. The whole system depends on one thing: wet pads. If the pads dry out, you still get airflow, but it's just warm outside air moving through the house.
The four usual causes of warm air
- Failed water pump. The most common cause. If the pump dies, no water reaches the pads and the air warms within minutes. You may hear the blower running normally while the pads stay dry.
- Stuck or misadjusted float valve. The float controls the water level in the pan. If it sticks shut, the pan runs dry; if the level is set too low, the pump can't pick up water.
- Clogged water line or spider tubes. Albuquerque's hard water leaves mineral scale that blocks the thin distribution tubes feeding each pad, so some pads stay dry.
- Worn or scaled pads. Pads hardened with mineral buildup stop wicking water even when everything else works.
Quick checks you can do safely from the ground
Before calling anyone, you can rule a few things out: confirm the cooler is switched to cool (not just fan), check that the water supply valve to the cooler is open, and listen for the pump humming when the unit runs. If the fan blows but you suspect dry pads, that points strongly at the pump or water supply. Climbing onto the roof to inspect the pan is best left to a technician, especially on steep or tile roofs.
When to call a pro
If the water supply is on and the unit still blows warm, the pump or float almost always needs service. These are affordable parts, and a technician carrying them on the truck can usually restore cold air in one visit. See our swamp cooler pump repair and general repair pages, or call us directly.