I am trying to blow up the trucks with the Nuclear equiptment and am trying to use the Thermal Key Pad after the guard punches in and goes through door. Having trouble figuring out how to do it and what the code is. Any help?

Put on the thermals before you interact with the keypad. You should be able to spot four that are a different color from the rest. The lat one the person touched will still have the most heat so it will be the brightest or most yellow. The first one will be coldest or more blue. Start with the bluest and work towards the yellow one.

Yep. Blue first, then greenish, yellow red. Its pretty tough and will take some time. You have to get there pretty quick.

Man it was a pain to get down, but it's so easy once you get the hang of it. I found it easiest to go by locations on the keypad instead of actual numbers. I also found it easier to turn thermal off before entering any of the keys. The moment you hit one the colors fade fairly quickly and you may panic & forget where the other 3 keys were.