Book startup in April, run it from May, expect the hardest work and a few humid days in July and August, and drain it in October before November freezes. Pick a month to see what to do from inside the house, what a technician does, and the local normals behind the timing.
Off season: the cooler should be drained and covered
January normals at the Grand Junction airport: average high 38.1 F, average low 17.3 F, 0 days at 90 F or above, average relative humidity 67.2 percent.
You, from inside or the ground
From the ground or a window, check that the winter cover is still on after windy days.
Look for new ceiling stains under a roof cooler.
A cooler technician
Nothing this month.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Nothing to book yet. Startup usually comes once nights stay above freezing, in late April or May.
Off season: the cooler should be drained and covered
February normals at the Grand Junction airport: average high 46.4 F, average low 24.1 F, 0 days at 90 F or above, average relative humidity 52.9 percent.
You, from inside or the ground
From the ground or a window, check that the winter cover is still on after windy days.
Look for new ceiling stains under a roof cooler.
A cooler technician
Nothing this month.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Nothing to book yet. Startup usually comes once nights stay above freezing, in late April or May.
June normals at the Grand Junction airport: average high 89.2 F, average low 56.8 F, 16.3 days at 90 F or above, average relative humidity 22.8 percent.
You, from inside or the ground
Keep a window or two open whenever it runs on cool.
Watch for drips or new stains under a roof cooler.
A cooler technician
If output drops, a mid-season check of pads, pump and water lines.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Weak or warm already? Try the troubleshooter, then send a repair request.
Peak heat: the hardest-working months, with more humid days
August normals at the Grand Junction airport: average high 90.9 F, average low 61.6 F, 19.8 days at 90 F or above, average relative humidity 34.2 percent.
You, from inside or the ground
Expect a few humid or stormy days when any evaporative cooler struggles. Switch to fan-only on those evenings.
Notice musty smells or weak air early, before a heat wave.
A cooler technician
Mid-season pad, pump and bleed-off check if the air is weaker or smells stale.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Problems now are repair requests. Mark it urgent if water is coming inside.
Late season: still some hot days, plan the shutdown
September normals at the Grand Junction airport: average high 81.7 F, average low 52.5 F, 4.2 days at 90 F or above, average relative humidity 38.3 percent.
You, from inside or the ground
Note anything that needs fixing before next summer.
Book a shutdown for October.
A cooler technician
Nothing this month.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Send a shutdown request for early to mid October.
October normals at the Grand Junction airport: average high 66.9 F, average low 39.5 F, 0 days at 90 F or above, average relative humidity 50.6 percent.
You, from inside or the ground
Once it is shut down, close or cover the indoor ceiling or wall vent so the duct does not let warm air out all winter.
A cooler technician
Shut off the cooler water supply and drain the line so it cannot freeze.
Drain and clean the pan.
Disconnect the pump and set the cooler so it cannot run on cool.
Cover the cooler, or close it up, for winter.
Note any parts that need replacing in spring.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Send a shutdown and winterizing request now.
November normals at the Grand Junction airport: average high 51.8 F, average low 27.5 F, 0 days at 90 F or above, average relative humidity 61.3 percent.
You, from inside or the ground
Check that the indoor vent is closed or covered.
If you are not sure the cooler was drained, book a shutdown now. Water left in the line or pan can freeze and crack parts.
A cooler technician
Shut off the cooler water supply and drain the line so it cannot freeze.
Drain and clean the pan.
Disconnect the pump and set the cooler so it cannot run on cool.
Cover the cooler, or close it up, for winter.
Note any parts that need replacing in spring.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Not drained yet? Send a winterizing request now.
December normals at the Grand Junction airport: average high 38.8 F, average low 18 F, 0 days at 90 F or above, average relative humidity 71.9 percent.
You, from inside or the ground
Check that the indoor vent is closed or covered.
If you are not sure the cooler was drained, book a shutdown now. Water left in the line or pan can freeze and crack parts.
A cooler technician
Shut off the cooler water supply and drain the line so it cannot freeze.
Drain and clean the pan.
Disconnect the pump and set the cooler so it cannot run on cool.
Cover the cooler, or close it up, for winter.
Note any parts that need replacing in spring.
Not sure how it is mounted? If you can only see it from a ladder, treat it as a roof cooler and leave the technician column to a technician.
Next step: Not drained yet? Send a winterizing request now.
Add two reminders to your calendar: book startup on April 15 and book shutdown on October 1. The file is made in your browser; nothing is sent.
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.
The numbers behind it
Grand Junction normals
NOAA 1991 to 2020 monthly normals, Grand Junction Walker Field (NOAA station USW00023066)
Month
Avg high F
Avg low F
Days 90 F+
Avg humidity %
Cooling degree days
January
38.1
17.3
0
67.2
0
February
46.4
24.1
0
52.9
0
March
58.3
31.7
0
41.3
0
April
65.8
38.1
0
35.2
2.9
May
76.8
47.1
1.9
27.8
55.8
June
89.2
56.8
16.3
22.8
257.4
July
94.5
63.9
25.6
34
440.4
August
90.9
61.6
19.8
34.2
349.9
September
81.7
52.5
4.2
38.3
121.6
October
66.9
39.5
0
50.6
4.9
November
51.8
27.5
0
61.3
0
December
38.8
18
0
71.9
0
NOAA 1991 to 2020 normals for Grand Junction Walker Field (NOAA station USW00023066). Long-run averages, not a forecast. Humidity is the monthly average, nights included.
Ready to send it in?
One form covers repair, startup, winterizing and replacement. Photos from the ground or from inside help.