why is my expy sitting low?

[expedition77]

I lifted the rear of my 2008 expy using a floor jack on the differential to replace exhaust.When i lowered jack to start vehicle,i noticed rear was sitting low.There is no air in airbags now.This was my first time jacking it up so im wondering if this is normal. I started it up to see if pump would start up but it didnt.What is going on and what do i need to do?Is there a way to manually start air compressor? Any help would be greatly appreciated.

 

[expedition77]

Who knew you should read the owners manual before jacking up your Expy?

Just read my owners manual.Dont jack your air-ride equipped Expy up unless you turn off air-ride suspension.You can do this in your message center.