I have a 2006 Scion Xb and just recently I have been having problems with the alarm.?

It has been very cold where I live (in the teens and lower) and when I activate the alarm, the doors lock but there is no beep. The red light is on the whole time inside the car, and there is no flashing blue light like there used to be. The red light was on only when the car was locked, and the blue light flashed when the alarm was activated. Now I drive around and the red light is staying on. What could be causing the alarm to stop beeping during activation? It does not beep when I unlock the car either. Thanks for any help!