Evaporative Cooler Not Cooling? Common Faults Explained

First, rule out how it is being used

A surprising share of “not cooling” calls are not faults. Before booking, check:

• Is there an airflow path out of the house, or is everything shut?
• Was it turned on early, or is it trying to rescue an already hot house?
• Is it a humid day, when evaporative cooling gives less relief?
• Is it in cooling mode with water running, not fan-only?

Our guide to using evaporative cooling properly covers all of this. If the basics are right and the cooler still is not doing its job, read on. Do not climb onto the roof or open the unit; the checks below are from the ground.

Air is moving but it is not cool

The water side is the usual suspect: the pump is not lifting water, the float valve is stuck so the tank is not filling, the water supply is off or restricted, or sections of pad are dry. Pads that are hard, clogged with minerals or worn out will not wet evenly either.

Little or no airflow

The fan or fan motor, a failed capacitor, the controller, or pads so blocked that air cannot get through. A cooler that hums but does not blow is usually a motor or capacitor job.

Water leaking onto the roof or through the ceiling

A dump valve that is stuck or leaking, a float set too high, a split water line, a blocked drain, or a tank or cabinet that has cracked. Water coming through a ceiling should be looked at promptly.

Cooler will not start, or the controller shows a fault

Power to the unit, the controller, a fault in the control board or the wiring between the controller and the roof unit. Note any code on the controller before you call.

A musty smell when it starts

Stale water and build-up on the pads after months of sitting. A proper service that cleans the tank and pads deals with the cause rather than masking it.

What we do

A local technician diagnoses the fault, and most evaporative faults are repairs we complete on the day: pumps, floats, dump valves, motors, capacitors and controllers are common parts we carry. We repair all major evaporative brands. When a unit is old, the cabinet is cracked or parts are no longer available, we say so and explain the options; see repair or replace an evaporative cooler.