1/4" SMC Valve PROBLEM

If it was that cold there could have been some water in the valve that froze and held the valve open. That probably held the diaphram open just enough to allow air to pass from the tank though the valve into the bag. If the valve is outside and its still cold driving it isnt going to unthaw it. Or you have some debris stuck in the valve....

I have 3/8 SMC valves and had a similar problem but with the lift valve sticking. My truck would have a corner on full lift when I came out every morning. After pulling the valve apart (very easy) I found that there was a few small shavings from the brass fittings that were just moving around inside. After a thorough cleaning, everything is good. The thread shavings were from screwing in a fitting, but I'm careful (I thought) not to over-do it on teflon tape, etc...

Good luck.