Been looking at TA at places to stay in Santiago and the top rated 2 B&B don't have a/c. Also noticed in travel guides not all hotels have a/c. Is it necessary at night?

I am not an expert on Santiago, but I spent 6 nights there last February when our plane had mechanical problems and then the earthquake hit. The airline had put us up at the Sheraton and obviously it was air conditioned, but we did find when we had to vacate the hotel in the middle of the night that it was surprisingly cool outside. So based on the 6 nights, I'd say that A/C isn't necessary, but as I said, that's based on only a short stay.

Wow, plane problems and then the earthquake-quite the trip! thanks for your response.

There is a big difference in day and night temperatures in Santiago. You often need a light top in the evening even in summer. Day temps in February will be around 30C average and night temps 15C or less. Santiago is also dry rather than humid.
Air conditioning is not that common here.

We have lived in Santiago for 2+ years with no A/C. Even on days when it is hot outside, it is cool inside our building. I didn't evac after EQ last Feb. (partly because it's more dangerous to go down the stairs and outside) but also because it was cold in the middle of the night. No worries-most buildings don't have AC here.

Thanks, jennhawk!

We were in Santiago last January and our room did have AC. We turned it on a time or two, but just leaving the window open at night we were comfortable. Loved our hotel (Meridiano Sur Petit Hotel www.meridianosur.cl). Well located in Providencia and the nicest staff we've ever had.