GD993C4

I just returned from a Sunday Morning ride and noticed a humming noise from the dash board after the car is turned off. I do not think that it is the clock. Any ideas as to what it could be? Thanks in advance.

GD993C4

I just did a search and will check it in 15 minutes. I guess search first and then ask questions!

NOH20

Gary,

Mine does the same thing. Let me know what you find out. I think this might be related to the HVAC controller. Something about a fan making noise, maybe not.

Brad

subdriver

Try this link:

https://rennlist.com/forums/showthre...75#post4196875

NOH20

This is exactly what I was referrng to.

Thanks Mark.

JasonAndreas

The fan located behind the CCU is supposed to operate for 20 minutes after you shut off the ignition, allowing the CCU to monitor the temperature in the rear engine compartment. If it is staying on longer and (draining the battery) see THIS thread.

g_murray

Yep, the "climate control system" does a LOT more than just keep you warm/cool when you are in the car/driving etc. It also monitors the temperature of the engine and will switch on the blower-fans even when you have turned off the engine, are out of the car, doors closed, game over, yada, yada, yada.
The buzzing/humming 'noise' is a tiny little fan that's at the rear of the CCU (climate control unit) that stays on for (up to) 20 mins. after 'shutdown' -- keeping the electronics cool whilst the unit does its job.
SOMETIMES a fault develops in the CCU which *prevents* the fan/unit from completely shutting down causing (eeeeek!) the car battery to go dead -resulting in 'not so much fun' when you are trying to get the immobilizer to disengage. It (i.e. the dead car battery condition) can also cause havoc to those cars with OBD-ii emissions (i.e. 1996 and YOUNGER) because all the 'readiness monitors' may need to be reset - as a result of the car's computer "losing its memory".

Gerry