Freeze Spray for electronics troubleshooting is still readily available from several different mfrs. http://electronics.mcmelectronics.com/search?cataf=&view=list&w=freeze+sprAY&x=0&y=0
Use it on pretty much a daily basis on the bench.
There are plenty of chemicals other than freon that evaporate fast and thus will "freeze" the components.
One time I realized too late that we'd forgotten to reorder the stuff. Can was empty, went to the stocking locker and none left on the shelf. So I went to the shop refrigerator, got a couple of ice cubes, crushed 'em, put them in a sandwich baggie with a little salt, tied it up tight with a couple of rubber bands and was able to use that to proof a leaky junction. Improvise, adapt and overcome.