Last week my driver's side washer wouldn't work. Next day it was fine. Friday it was out again. Kept trying it as truck was driven 20 miles in afternoon and would not work. Then at 9 pm after it sat several hours and it had gotten colder outside, I went out and it worked fine. So I don't think it is freezing as it came back when it was colder (or did the heat keep sinking in from the engine bay while it sat 4 hours?) and the other side never quit. Worse is that the hoses route under the cowl pannel which would be near impossible to pull (made a mess pulling on on my old '84 F150). I do have a mix of cheap washer fluid (rated to well below zero F and some of that Rain X stuff but can't remember if it was in for both times the washer quit). Not blocked by snow either.