!995 320S AC blower problem

Suddenly noticed that the blower speed will not increase in speed past the auto (mid) position. Varies normally below this. Seemingly unrelated the air temp stays cold no matter the setting. Defrost is
mid speed cold but throught the correct windshield vents. These seem unrelated but occured on the same day. All other funtions are normal. Any thoughts on this Al
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Sounds like you lost your blower regulator. How many miles on the car? Do you have air slots across the hood near the windshield? When was the last time you replaced the vent filter? If you do not have slots, you need to replace the vent filter every 15,000 miles. If you have slots, you need to replace vent filter every 45,000 miles. Lack of proper maintenance, i.e. replacing the vent filter when you are supposed to as recommended by MB, WILL cause the blower regulator to overheat and self-destruct. The filter plugs up and cuts off air flow to cool it. The filter is in the engine compartment mounted above the blower regulator, which is mounted on top of the blower. As the Fram commercials used to say, "You can pay me now or you can pay me later". This is an expensive 'later'!

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The car has 80,000 miles. Checked the filter area and there is a u or v shaped screen unit that is clean but no filters over the screen. Guess the blower regulator and the mono valve could both be bad unless the blower regulator could affect the temp. Thanks for your reply Al
Al wrote:

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What filter did you check?? You cannot see the vent filter until you remove the massive cover. Open the hood. Get a phillips screw driver. Along the firewall you will see a large black plastic cover that goes between the control module cover and the master cylinder, almost the width of the car. On the pass side, you will see one or two vacuum lines connected. Disconnect them. Now remove the 6 black headed screws holding down the cover, 3 along the pass edge, 1 in the middle front, 1 in the middle rear, and 1 by the master cylinder. Lift up the passenger end. Look down, there is the filter. Lift it out. Now you will see the blower motor with the regulator mounted on top of it.
And, your 140 does NOT have a mono valve, it is a DUO valve. Totally different and not serviceable. Rare to have it go bad, it is a big improvement over the previous mono valve.

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There is a small panel on the passenger side of the large panel that you describe. It is held down by 2 TORX screws Believe it or not I have the correct size. That is the one I checked. Guess I need to look further at the large panel you decsribe. Mine uses small TORX screws and 2 very large I believe Phillips screws. The parts houses are calling the other item a Mono valve but in looking at the photo of the part I can see that Duo fits the appearance of the part. Is it dual electromagnetic? They are probably using old terminology. Thanks again. Al
Karl wrote:

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Sounds like your air intake filters are plugged... you have to remove alot of trims along the windshield to get to it.
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