what could be causing vibrations coming in at the back of the radio area

[Florence]

in neutral and under load, a chattering noise and vibration appear to be generated towards the back of the radio/air con control panel. it increases with revs. local air con guy and several local mechanics are stumped!

 

[krusing]

turn the Air Con off, as it could be a TX Valve on the evaporator [in the dash] that could of gone faulty,
also the could be an air lock in the heater,
or rubbish in the Heating/Cooling Fan housing.