The trip we took in 2004 was the last one where we used our AC much at all. In Whitehorse it was 94°F the afternoon when we pulled in to the Hi Country RV Park and the same a few days later in Dawson Town. People without ACs were not comfortable sleeping. In Dawson the couple next to us was from eastern Canada and didn't have AC in their rig. The woman ended up the next morning, asleep on the picnic table next to our camper. Interesting sight that early in the morning as I opened the shades to look out.
Then when we got to Fairbanks it was both hot and smoky from the forest fires. The AC made a big difference is being able to sleep at night and not get smoked out. We only stayed a day or so and headed for Valdez and smoke free air.
This is actually the only time I can remember using our AC in the north country but was sure glad to have it that summer. On our last trip in 2011, we got by just fine with our fantastic fans for ventilation in the evenings. I have a built in AC in my truck camper but didn't start it a single time on the entire trip. I started it prior to the trip to make sure it worked and again when we got back, just to check it out.
In 2009 we had ice on the windshield, the morning we pulled out of the Hi Country RV Park to head up the Alaska Highway and the truck outside temperature gauge was showing 32°F. So you never really know what you will fine, but you can always move around the north to find better weather most of the time.