Replace insulation in a Trane HVAC? (TWE030C140B0)
If the evaporator has to come out, you'll likely have to recover the refrigerant first.  Unless you have the proper equipment, you're not going to be able to do it yourself.  Even if you have the equipment, you may also need to be certified to complete the work.

If you can replace the insulation without removing/damaging the refrigerant lines, then you might be able to do it yourself.