There are 3 screws at the top, the quarter-turn, plastic lock at the center console, and another screw on a small bracket protruding from the outside kick panel. There is also a screw in the middle, holding the two under-dash panels together. So that's 5 screws and a quarter-turn lock.

Once those panels are out, there are 4 screws holding the fan in place.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Pull the panel down slightly and then back towards you. It should pull out of the rear slots that hold it up. The sampler motor attached to the panel and there is a rubber hose that runs from the sampler to the display on top of the windshield. disconnect this hose. (It is a pain to get back on, but you can with patience.) You can either pull the sampler out of its clips or pull off the wires going to it. I have done it both ways and it is a little easier to reattach the hose with the sampler free of the panel. The sampler just pushes into the clips holding it in place.

When you are putting the new fan in place put the long phillips head screw you took out of the fan cover through the front screw hole and temporarily screw it into the air plenum. This will hold the fan in place while you screw in the fan attaching screws. Then back this screw out and install the fan cover. Make sure that the cover seals and that the fan wires are going out through the provided slot.

Before you tighten everything up, turn the key to the second position and make sure that both the blower and sampler fans work. Put the blower on high, auto and low to make sure it spins at all speeds.

When you install the panel, first slide it in and line up the air passage in the panel with the air duct coming from the center console. Then stick the panel into the slots at the rear (firewall side) hook up that darned sampler hose then carefully line up the three screws in the front. You will probably needd a small flat bladed screwdriver to manipulate the metal clips the screws go into.

This should all take you under an hour.

Good luck!

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Thanks for all the input.

O.K i I got to the blower motor as per all of your info. I pulled the two wires off the motor an put 12 volts to the motor and it works great.With the key on,i am getting power from the two wires the go to the motor.I am confused.

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Blower motor control is kinda counterintuitive. The blower gets constant +12V through one wire and varying voltage through the other - high voltage for low fan speed and low voltage for high fan speed. IIRC the contoller puts out close to 0V at max and something like +11V for min. Roll the temp wheel with the blower set to auto to check intermediate voltage noting that the controller responds slowly to changes.

You can also check upstream of the controller. That's more straightforward. IIRC the controller sees from the PBU 0V or close to it at min and 7V(?) at max.

When supplying power directly to the motor, set it at the same orientation as it is when installed - pointing up. This orientation puts the greatest load on the bearings. Many motors that won't work when installed test perfectly fine horizontally. If you can move the shaft along the axis of rotation, get a new motor or get some new bearings installed.

Sixto
87 300D

I never took the BM out of the car as you can see in the picture.The voltage remains the same when rolling the wheel.Also the monovalve hums until i roll it down[on blue] until it clicks on max,then it stops.

Does the monovalve have anything to do with the Blower Motor coming on?

Nope. Unrelated circuits downstream of the PBU. Neither monovalve nor blower has electrical feedback to the PBU. The most they can do is blow the system fuse.

Sixto
87 300D

I know nothing about electrical stuff,so what do you think is the problem?

Let me see if I can explain what you are seeing on the meter. In automatic mode there will be voltage on both. One should be +12v (batt.) and the other should vary (0-11v) realizing that 0-to-11 is more "negative" than 12. Showing 12volts on both pins means there is no difference between the them and no current flow. (Think along the terms of water pressure.)

Have you tried the fan in Hi/Lo vs. Automatic?

If the blower will not work in Hi, Low or Auto, and since it spins fine when connected to the battery, I would check the pushbutton controller. It gets more mechanical wear and they are notorious for intermittent solder cracks at the points where the circuit boards join. Do a search of "resoldering" and you should find pics. It is a pretty simple repair but if needed, find a buddy that can touch it up for you.

The "humming" of the monovalve tends to point to the temp. controller but the pushbutton controller turns it on. Since you are getting a semblance of control by varying the temp wheel, I am thinking it should be working.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

The blower regulator is bad.
Fastlane:
http://catalog.peachparts.com/item.wws?sku=W0133-1598146


The regulator controls the blower ground = regulates power through ground for speeds.

No ground = no motor speeds.




Have a great day.

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At this point, Roy, I don't think the data is available to confirm whether it's the blower regulator or the CCU.

That is the (failure prone) porcupine regulator, not the earlier triple coil resistor unit.
If anyone local has a spare, I suggest you borrow it for diagnosis, and buy it if needed, it would save serious money.

Agreed, but I'd hate to pay that kind of money just to find out that the CCU isn't providing the voltage to the porcupine.

I'm going to buy one of them on e-bay as a spare...........just for such a situation............it's very difficult to confirm whether it's the CCU or the porcupine.

My blower motor started becoming noisy about 6 months ago. Finally got to the point where I decided to do something about it. Found a used W126 unit on Fleabay for $50, so I decided to attempt the repair myself based on the information above. (By the way, thanks guys!!) When I removed the old unit, look at the pictures to see what I found:

I haven't a clue what the mess is. There are no bodies or dead bones mixed in, so I figure it's not of the animal variety.

Anybody ever seen something that looks like this before?

I popped the new unit in, and it works like a charm, but I didn't know things like this "grew" in blower motors...

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