2013 prostar A/C

Pull the AC air filter in the engine bay. It's upper left side, you'll have to get high.

 

Fan speed is controlled by the dial, then voltage is regulated by the linear power module. One or the other could be defective. The blower motor itself could be going too.

 

depending on build date there is a field campaign for the blower motor and lpm. also make sure the fuse isnt loose. they tend to get damaged when the fuse box gets pulled off

 

My mechanic has said he has been repairing quite a few a/c condensers in the sleepers of the Prostar.

 

My 2010 at Crete you fix it the Crete way. Take a 20lb dumbbell and bang the area in front of what would be the passenger's side shins just below the knee. It usually frees up the fan.

 

I had a 2011 Prostar and now have had 2013 Prostar for a year. Same thing has happened with both. Had the first one checked out several times. No codes registered on computer. After several hours, another tech came on duty and said "aaah thats simple" He walked over to the passenger side and hit the bottom of the dash and the AC started working again! It was explained there is a bad spot in the armiture where the brushes arent making contact. So a "Fonzie" maneuver does the trick. Has worked everytime

 

Still could be where the breaker sits in the fuse panel with worn or loose sockets. Haven't experienced what you described, but certainly possible. Like Dutch mentioned, there are recalls for the blower motors within a specific build range, lots of them.