When I turn on the ignition, without starting the motor on my 96 Coupe, an incredibly loud whistle sound comes from the upper part of the motor compartment. Sounds almost like a pressurized leak - like feedback from a loud speaker. Lasts for about 7 seconds and tapers off to nothing as if it ran out of air pressure. Does not always happen. Always seems to happen when I forget to disengage the immobilizer system. Happens with A/C turned off, stereo turned off, and without the motor running. Any ideas out there? Thank you.

 

Mechanic said its a blown diaphram in the varioram