3691 Error Code For Interstate Tractor Tractor Models
There are 2 kind of error description.
ISM-DI Glow Plug Circuit. - No Load Error For Low Voltage System Engine
F5C Glow Plug Circuit. - No Load Error For Low Voltage System Engine
Partial frosting and sweating of lines combined with poor cooling, fan belt slipping, loss of refrigerant, restricted or clogged liquid line or expansion valve malfunctioning.