Bonnet temperature? Do you mean just feeling the temperature of the metal? I really doubt that would give you any meaningful information.
Dust on the outside of the radiator is likely going to be insignificant, particularly if the fan is working properly. Can you hear the fan starting up when stationary? When was the last time you flushed your radiator?
Dust on the outside of the radiator is likely going to be insignificant, particularly if the fan is working properly. Can you hear the fan starting up when stationary? When was the last time you flushed your radiator?
I can feel the fan starting and working when stationary and blowers working without engine getting started.
Radiator flushing, I am not sure I have ever got it done, except if service guys do it as normal part of their service routine.