My air suspension isn't turning on anymore on 2007 Chevrolet Avalanche

I have a 2007 ltz avalanche and the air suspension used to come on for about 10 seconds every time I would start it but for the past few weeks it doesn't turn on and I dont get any warnings that something is wrong. What gives?

Asked by for the 2007 Chevrolet Avalanche
Is the level of the truck alright?