So, provided you have all the pieces, heres what yuoll have to do to get things going.

-Drain the coolant and remove the dash (already mentioned in the above link).
-Remove the vacuum lines going to the servo and associated hardware. NOTE: you will only need to keep 2 vacuum actuators. The one above the blower fan and the one behind the heater/evap box that works the vents to the rear of the car. Everything else can go.
-Remove the wiring harness for the HVAC/servo system. This is somewhat easy as its all one piece. It starts at the grounds that are in a bundle in the forward passenger front fender and goes all around the car to an inline fuse in the relay box and a connector for a temp probe in the firewall. Between that there are assorted plugs that need to be disconnected, a single ground connected to the steering wheel support, power from the fusebox(#12 connector for the fan). The whole mess comes right out.
-remove ACC servo and assorted hardware(brackets, piping, aux water pump)


In the end, you will have this mess…


In case you weren’t sure of what it looked like, Ive pointed out the ACC servo for you. No need to thank me


The easy parts of the install will be installing the heater valve, the coolant pipe that feeds it and the Bowden cables that actuate the valve. These are all plug and play.



A couple small notes though. The Bowden cables need the grommets and small spacers that seal the bulkhead. I had forgotten those and had to source new ones at the hardware store. The bowden cables are affixed by “C” clips. You will need a tool for them as well. The heater box is fed through 3 ports, the heater valve takes care of two. The one remaining port on the drivers side will be fed by the existing heater tube that had previously fed the lines to the ACC servo. Even though it has a slight bend in it, there is enough flex and slack that it lines up with that remaining heater box tube very well.




This cable and lever go to the fan controls. The lever needs to be changed from the vacuum actuator to the manual cable lever. The cable mount needs to be added as well. There are two rivets in the place where the mount would be affixed. I couldn’t get to those rivets to remove them and reuse the holes, so what I did was to make a new hole under the heater box and add a rivet there. For additional support I added a brace and riveted that to the heater box as well.




This vacuum actuator was swapped from the 240D. It’s a pretty cool and burly unit. Mainly I swapped it and its mount because it actually held vacuum (and the ports line up with the A/C dial/controller). I removed the old vacuum pod and its mount. There are placeholder rivets where the new mount should be located. I drilled those out and riveted the new mount in place. Theres also a small clip that connects the actuator rod to the flap, don’t forget to get that as well.




To the left you see the cable for the slide actuator for the floor/dash vents and its mount. The mount is pretty easy, remove existing rivets and rivet the cable mount in their place. The lever that actuates the vents is interesting. On the 240d its welded on to the shaft. I ground down the weld and removed it from the shaft it was on. Its keyed in a “D” shape so it can hold to the shaft. I used the old spacer (also keyed with a “D”) and press fit the new lever onto the shaft. Its then fixed there with doubled up clamping washers. The return spring is also a transferred item from the 240D. Between the cable mount and lever arm (a little south) are two rivets with their heads drilled off. This was where the mount for the old wiring harness was located. It needs to be removed so everything in this area fits.




On the left side of the heater box was the old vacuum pod and lever arm for the floor/dash vents. There was normally a plastic shroud to protect the wiring harnesses from the lever and its movement(so it doesn’t try to cut the wires), but when the new levers/cables were added its range of motion interfered with the shroud and limited the vents movement, so the shroud was removed and the lever arm cut. The vacuum pod was also removed




First picture is of the switch panel mounted. You cant see it here, but the rivet holes (remember it was riveted to the heater box) on the bottom needed to be enlarged. The auto climate panel has a stepped mount and a raised and threaded screw insert. The new panel needs to fit over that threaded insert to mount flush on the heater box. Some appropriately sized washers corrected the height difference and the new panel was bolted back on.

Second picture is of the vacuum lines going to the A/C control. Top left is the main vacuum feed from the engine bay. The two on the right go to the vacuum pod over the blower fan. The bottom left tube(blue) is spliced into another tube. That tube feeds the vacuum pod for the floor vents. In the 240D that pod is on the right side of things. In the 300CD its on the left. I needed to add a bit of length to the vacuum line to get things connected.


Picture of the vacuum pod in question.

Continued

Gavin