Do you mean it has runs??
One thing about acrylics is dry time...they need to be thin enough to spray, but thick enough to cover.
That said with the cold temp and 30psi I suspect you are trying to get too much coverage in one coat.
So what to do now....if the surface has a lot of runs, strip or sand depending on what you have, reprime and let dry.
30 psi will work fine...but you will need to adjust your distance for your airbrush and paint thickness...in short, the paint, pressure, pattern of the brush, and
distance to surface all factor in. I prefer lacquers for many reasons, but acrylics have a lot of advantages going for them.
Do some searches here or in tips and tuts..there is a lot of good advice posted