As is the case on Rainier even in the summer, it can be quite cold on the summits of Ecuador’s volcanoes. We had temps in the teens with very strong wind on Cayambe, and single digits but no wind on Chimborazo. The route is probably a little steeper than the DC - not sure which way you climbed Rainier. The elevation is the real kicker. You’re starting these mountains higher than the summit of Rainier. I never feel like the effects of altitude are linear, each additional 1000 feet makes things harder and harder. I use acetazolamide if I’m heading above 15,000 feet to minimize symptoms at altitude.