My '99 CLK320's climate control acts funny periodically. At times, the fan speed will speed up and slow down sporadically. It also often makes lould whirring, and wheezing sounds. It is quite annoying, and I usually have to take it off of "auto" and turn the fan speed all the way down to reduce the sounds.

Any idea what this could be?

 

If you have it set under FULL AUTO, then yes, the fan speed will change according to the environment, i.e., if you are driving fast the fan will slow down, if you are stopped then fan will flow faster.

i keep the temperature setting to auto, and keep the fan speed between 3 & 4 bars, that works for me, and no noises.

If the noise is bad, take it to the dealer, it should still be under warranty.

 

It does speed up when I slow down, but the changes in fan speed seem way too "jumpy." It also wheezes loudly...

...my warranty is now expired....

 

Also....what is the reasoning for it speeding up when I am driving slow, and vice versa???

 

well, basically, when you are driving faster, air from the vent circulates faster throughout the car, therefore the fan's speed is decreased. When you are driving slow, the fan speeds up or else the rear cabin doesn't cool or heat up like the front of the cabin.

Does that help?

 

My climate control did the exact same thing....my dealer replaced the entire blower system....all fixed...

 

Do you have any idea what it cost?

 

It's probably a bad blower motor voltage regulator. Pretty common problem, easily fixed.