1980 300D Servo ACC To manual 240d ACC conversion

[Matteo_300D]

converting the dreaded servo system to a 1981 240d manual system and cant find anyone who tells what to do with the differences in the heater hose routing. Mainly I'm wondering what the lines indicated with blue are for and if they can simply be deleted and the remaining hoses rerouted to make the system look like the 240d connections or if I'm going to damage something by doing so. the line ending with 332 says it goes to carb/choke box and of course doesn't exist under my hood.

thanks, Matteo

[cfh]

I did this years ago on my 300cd. I swapped the entire HVAC box under the dash with one from a 240d, the valves and hoses, and also the controls and the wiring harness. I ended up with some odd bits of extra wiring under the hood that I just hid and taped off.

I’m sure the conversion could have been done more efficiently but it was a very satisfying project and looks factory (until you notice the wiring hidden in odd spots under the hood). I have since gutted another complete manual system from a junked 240d “just in case I need it” down the road for another car. I like the manual system much better than even the newer AC III set-up and might put it in a 300TD wagon I plan to get on the road hopefully someday soon.

When you have the dash and the HVAC box all out of the way it is easy to add sound deadening.

[Matteo_300D]

I"m doing mostly the same. pulled a heater assembly from a 240d at the pick n pull and installed it into my 300d. coming along good so far. I pulled out most of the old harness as well then I rewired the harness from the 240d to allow the aux fan to come on at the same time as the ac compressor.

at this point I just need to hook up the compressor and aux fan, finish interior wiring( i didn't use the thumb-wheel and temp sensor from the 240d, I installed a 300d etr switch and a toggle switch setup to run the ac at max cooling all the time), and then reinstall the dash and instrument cluster. And replace the drier and charge the system after all that

[Matteo_300D]

well, to answer my own question, yes you can. just re-plumb to match the 240D heater plumbing and delete anything extra. btw a 3/4" heater hose fits nicely on the 240d manual valve and is a very tight fit on the thermostat housing(its larger and takes some effort and spit)

[Matteo_300D]

the heater works better than it ever did since i changed the heater box. I flushed the cores before I installed it so that may be why. the ac is a sanden conversion with stock condenser and a R134a charge and it will when driving blow 40 Deg at the vents 55-60 Deg when idling. the blower seems to blow stronger than the original(yes it had been oiled), but that could be because of the control over where it blows out.