I’m getting this exact problem too. The first time I activated the fan, I missed getting up the ladder before it started spinning too fast, so I was stuck under it. I sat there a while to see if I could figure a way out, and then died trying to climb up. The fan was spinning at full speed during this point (and I didn’t crash). Second time, activated the fan, made it up the first ladder, climbed up the second ladder, and just as I turned around, dismounting the ladder, the game crashed (hl2.exe has stopped working). A third time yielded the exact same result. Not sure if this has something to do with the fan itself or getting to (or looking at) a certain point after activating the fan, but I am now stuck and can’t get passed this.
There was only one other time I had a crash and that was at very beginning of the silo chapter, as the army of Houndeyes rushed me, the game randomly crashed. Hoping to get this fixed soon so I can continue playing this awesome remake!
Edit: Tried again, this time only climbed up the first ladder to get above the fan and then stared at it. Within a second or two of the fan starting to make it’s buzzing/humming sound as it spun up, I crashed.
Edit2: Decided to noclip passed the fan portion and everything seemed to work fine. I opened the fuel (or whatever it is) valves and went on my way, as I zoned into the previous (next) area, my game crashed on the loading screen.