Heater Box Rattle Sound!

[simmiv]

My Landcruiser HDJ100 2003 Sahara model has begun to create this intermittent rattling sound.  As far as I can determine it comes from the heater box behind the radio/aircon panel.  The rattling sound occurs when driving or stationary, when the aircon is on or off and even with the engine off, but the power switched off.  I'm suspecting one of the flap motors, but not sure.. 

I've recorded a video with the sound which you can play/download here 

https://sites.google.com/a/valgeirsson.com/electronics/Home/Landcruiser Rattle 2022-12-13.mp4?attredirects=0&d=1

The video has two photos at the beginning and then three instances of the rattling sound.  The first two with the engine running and the last one without the engine running..  

I hope someone has heard this before, and yes I know if it's the heater box and it has to come out it's a major exercise!

Rgds,

Simmi

[simmiv]

This is a Sahara model with automatic aircon.  After a fair bit of research, I did finally manage to find the correct wiring for the Air Mix Servo Motor..  It is driven by the A/C Control/Amplifer unit.  I also found out that you can hold down the Auto and Recirculation buttons while swithcing power on.  This will cause the ECU in conjunction with the A/C Control/Amplifer to run diagnostics on all the motors and then display error codes called DTC..  I got DTC 21 and 41 flashing alternately..  DTC 21 indicates that the solar sensor is open or short..   That one was easily fixed..  I have a dash matt on top of the dash and of course it was blocking the solar sensor.  Once moved out of the way and running the diag test again, I only got the 41 error, which says "Abnormal ari mix servo-motor operation".  With the correct wiring I could measure both the power to the motor and the voltage feedback from the resistor devider which tells the controller where the mix blade is located.  The sensor voltage goes from 0v to 4v depending on the temperature settings.  That measured fine based on my testing.  Also, the drive voltages for the motor swing from + to - depending on which direction the motor is being driven.  Once again I could see that was ok.

I then simply removed all the three connectors from the A/C Control/Amplifier and used contact liquid to clean the contacts of all the plugs.  I then replugged it back together and now it seems to work fine.  The diagnostic comes up without any errors i.e. 00 which means "All sensors normal"  I gues the sense voltage and/or the driving voltage had some poor contacts causing this rattling to occur..    Hope this helps others..

Rgds,

Simmi