Congratulations.

Before you mess with the modulator, make sure the VCV on the injection pump is working correctly. If it is giving the wrong vacuum level to the modulator, it isn't the modulator's fault.

There really isn't a good place to drain the air cleaner box, should you want to do a Federal retrofit. Others have installed a catch bottle and pour it back into the sump once a month or so. IMHO, the drain goes to a fitting in the upper oil pan which is not trivial to swap out.

The kickdown switch under the accelerator pedal could be bad, check the switch first. Then check Klima and its connections -- kickdown goes through Klima, which prevents kickdown from working if the engine is already within 600 rpm of its rev limit. If Klima has failed or partly failed, kickdown will not work. As part of the diagnosis, you can short Klima pin 5 to pin 6 and see if that makes kickdown work.

Klima also turns off the a/c compressor's clutch -- there's a microswitch on top of the valve cover that is tripped at WOT. It's possible that the decrease in vent airflow is related to that. However, the defrost being always on suggests you have one or more bad pods in the climate control system, which makes the analysis harder.

First thing in any case is to go through the car looking for vacuum leaks -- cracked plastic hoses, rotten rubber connectors/splitters, bad vacuum pods (a/c and door locks), leaky vacuum reservoir (in the trunk), etc. The 123s are heavily dependent on vacuum for many functions.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

The other thing strange about the blower is that while heavy throttle the problem starts, but it does eventually blow full speed again. Very strange.

Anyway, does clockwise soften or harden shifts? I'll be sure to check the VCV before I adjust...

I'll try that pin short on the KLIMA... updates coming.

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'90 300SE --- 173k miles --- (Odometer just stopped working!)

'85 Cali 300D --- 193500 miles --- (Second one) Sold Nov '10

'82 300TDT --- 236,xxx miles --- (My first one) Sold July '09

I have no idea, never touched any of mine. Others will know . . .

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

IIRC it is CCW to soften

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83 300SD Dark Silver Dark brown inside

Time for pictures and a signature modulation.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Fine!! Here's some pics! Geez! She's still very dirty on the outside. But here's a couple pre-lims. Took these just before I bought the car. Started cleaning the car straight away. Looks good so far. I need to finish my hand-scrub inside and out and wax it.

I took it to the wand-wash and pressure sprayed the engine and under the car. The car said "that tickles!!" I think.

__________________
'90 300SE --- 173k miles --- (Odometer just stopped working!)

'85 Cali 300D --- 193500 miles --- (Second one) Sold Nov '10

'82 300TDT --- 236,xxx miles --- (My first one) Sold July '09