Needing some help

Probably has the advanced microprocessor like the '04 I used to have.

If manual defrost is failing, it's gonna be something going on in the unit versus trash in the evap case or other easy fix.

If I were you, I'd open the electrical box (behind the control panel) and check fuses and look for anything loose/rusty/burned up/obviously not right. Also look over the refrigerant plumbing to make sure any switches/sensors are positively connected and no loose connectors/wires hanging around.

If I spent an hour doing the above and didn't find the problem, I'd be on my way to a Carrier dealer instead of wasting more of my time. Especially if I had product in the van.

 

Yes sir. save your sanity and maybe the next load.