pressurization where higher is lower.
Brian,
In level flight at cruise with a complete pack(s) failure the cabin pressure differential will fall, not rise, as higher pressure inside the cabin will leak overboard into the lower ambient pressure outside the jet. With the cabin pressure leaking overboard and the differential pressure in the cabin decreasing, the cabin altitude will ascend, rise, and get further away from sea level pressure until there is no differential between the pressure inside the jet and the pressure in the surrounding atmosphere.
The temperature outside the jet at normal jet cruising altitudes is 55 degrees Celsius below zero (-55C) plus or minus a few degrees. Without a means to heat the cabin the temperature will rapidly cool.
At sea level, where your altitude is low you have higher ambient pressure. As you go up in altitude, go higher in the atmosphere the ambient pressure drops, it is lower. It is an inverse relationship: higher altitude yields lower pressure, lower altitude higher pressure.