From Latacunga drive to Mauchi then follow the dirt track up to Los Illinizas. There’s now a control stop part way up the road, register here. If your intention is to summit without a guide they might not let you through – careful what you say! From the car park its 1.5 to 2 hours hike up to the refuge. The refuge cost $10 or night or theirs a nice campsite right next to it.
The easiest route up Illiniza Norte is from the eastern ridge (right of the above picture): a clear path from the refuge will take you to the starting point. From their its a basic scramble to the top. It’s not a technical climb, but snow and ice can make the final ‘Pasa De La Muerta’ a challenge. When we went an 80 degree snow wall lined the summit.
If you have the kit, stunning routes up the South face (pictured above) remain to be climbed.