quick question.. maybe someone went through this experience before..

my w124 (92) a/c works really good. original. i noticed after driving 20 mins or more, the blower starts slowing down. no problem about the coldness. its the blower that wears down after a while. i can always switch to "auto" or high and it will blow stronger thus making it really cold.

is it the blower??

what do u think?

 

It's an automatic climate control system. It controls the temp and the fan speed to maintain the temp you set on the dial. Just leave it on auto, and set the temp wheel where you want it. I pretty much leave mine at around 75 all year round.

 

Paul is probably correct and you are just experiencing the normal modulation of the blower.

Also, be aware that the HVAC computer controls the blower speed by its current draw rather than voltage. The HVAC computer calculates the current draw setpoint based on temperature requirements and then gives more or less voltage to the motor until it sees the desired current draw. Kind of a strange way of controlling it, but it makes sense. It's possible that something causes the motor to increase friction as it warms up and then it draws the same current while turning more slowly. I would think this would be accompanied by a squeeking noise.

This info came from my interpretation the service manual, and the fact that I do HVAC controls for a living.

 

The W210 regulators were notorious for making a "squeeking" noise. It wasn't the motor but the actual regulator making the noise. Weird stuff!

 

thanks for the input guys.....

i set it on "auto" although the air stays on high blower i manually depress it since it gets really cold. i'll try setting the temp to 75 as advised... i'll let you know.. thks!

 

this is exactly what i do as well. auto, 75 all year. cool enough in heat and warm enough in cold. less wear on switches and so on. i generally keep it on the econ position and only use the AC when necessary.