Spring startup

Start the cooler before June heat

In the Grand Valley, startup usually fits late April or May: nights have stopped freezing, and the hot stretch has not started. NOAA normals put May's average high at 76.8 F and June's at 89.2 F, with 16.3 days at 90 F or more in June. Book in April.

Request service See April in the planner

What startup covers

A full startup, step by step

What to expect a technician to do on a roof or side cooler. If something on this list gets skipped, ask why.

Technician startup checklist

Take off the winter cover and check the cabinet and pan for rust or leaks.
Reconnect the water line, turn the water back on and set the float level.
Clean out the pan and replace or inspect the pads.
Check the pump and the water distribution lines so every pad gets wet.
Check the belt, the motor and the blower.
Check the bleed-off, if the cooler has one, so minerals do not build up.
Run it on cool and on vent, and check for leaks.

Ground-level evaporative cooler cabinet opened up, showing the blower wheel, belt, motor, pump and water pan, with its pads and louvered side panel leaning nearby and a garden hose on the patio — A ground cabinet opened up, with the pads and side panel out. Image credits

Your part, from inside

Open or uncover the indoor vent if it was closed for winter.
Open a window or two before you switch it to cool.
After ten minutes, feel for cool air and listen for water.
Watch the ceiling under a roof cooler for a few days.

Safety first. Roof work, the inside of the cooler cabinet and anything electrical are jobs for a cooler technician. Every check on this site is done from inside the house or standing on the ground. Nothing here asks you to climb a ladder, open the cabinet or touch wiring.

Timing

When the valley warms up

Average highs by month at the Grand Junction airport. Startup belongs before the climb.

Average high by month, Grand Junction (F)

Questions

Startup questions

How early is too early to start a swamp cooler?

While nights still freeze. The average March low is 31.7 F and April is 38.1 F, so a line filled too early can freeze again. Watch the National Weather Service forecast for the year you are in.

Do I need new pads every year?

It depends on the pad type and how hard last season was on them. Ask the technician which pads you have and when they will need replacing. Musty smells and white mineral crust are common signs they are due.

Can I do the startup myself?

On a roof cooler, no: startup means working on the roof, inside the cabinet and on the water line. Your part is inside the house: open the vent, open windows, test it on cool, and listen and feel for problems.

What does a startup cost?

No prices here, on purpose. Ask for a written price before any work starts, with the parts named.

Sources

Read or re-read on 2026-11-06 MT. Each line says what the source backs on this page.

U.S. Climate Normals, 1991 to 2020, NOAA National Centers for Environmental Information. Monthly normals for station USW00023066, Grand Junction Walker Field: average highs and lows, cooling degree days, days at 90 F or above, and relative humidity.
Grand Junction, CO forecast office, National Weather Service. Current forecasts and freeze warnings for the Grand Valley. Use it to time startup and shutdown in a given year.
Building America Best Practices: Energy Renovations, HVAC (2011), U.S. Department of Energy, prepared by PNNL and ORNL. Evaporative coolers can use about one quarter as much energy as central air conditioners; direct coolers can lower air temperature 15 F to 40 F; a window or vent must be open; at least two speeds and a vent-only option are recommended; they need regular maintenance; water costs should be counted.

Book a startup

Say where the cooler is mounted and whether it was drained last fall.

Request service