Screenwash won't gel up if it's actual screenwash, diluted properly. It has a high concentration of methanol or Iso Propanol when neat, with maybe a little ethylene glycol and perfume/detergents in small concentrations.
That's not going to gel neat or even diluted 4-fold with an effective alcohol content of at least 20%
Algal or microbial growth will potentially cause gelling if you're partial to filling your screenwash reservoir with water and a dash of washing up liquid in the Summer.