What is this thing?!
 

Sorry I can't take a pic, someone borrowed my camera...

There's this thing in the engine compartment on the front passenger side fender, right in front of the coolant reservoir. It looks like a little metal box a few inches on a side with lots of holes in it, and inside are various coils of wire. There is an electrical connector plugged into the back side of the box.

What is it? What does it do? This has boggled me for years and I kept forgetting to ask until now.

It's a toaster, you must have the camping option, 673, on your wagon..

... Really it is the resistor for the HVAC blower motor.......

Don't mess with him....
it really is a toaster ... for croutons....

Thanks for clearing that up!

YES! You can toast your croutons that you get in the little baggies when you get your salad from Wendy's. After a few minutes of driving, park, pop the hood open, and put warm croutons on your salad. Sit down on your hood, and enjoy. DELICIOUS! :p :D ;)
-Joe

Resistor
 

Is that used to vary the speed of the blower motor?

yes, for the blower motor

OK what if this 'toaster' device malfunctions? The blower in my daughters '83 300CD doesn't work. Should I be looking at this device as a possible cause?

Yes you should...
Don't quote me on the following...
You have an electric motor which does not change speed according to which ' windings' are connected.... but based on the amount of ' juice' applied to it..... so these are resistors used to vary the amount of juice sent to that fan to give you different speeds....
As soon as someone tells you the true story I will delete this...

81Wagon,

Substitute the word voltage for "juice" in leather's answer.

You only have "juice" if you have the MB orange squeezer option along with the MB toaster option. LOL

P E H

hey, I have one of those on my SD and I've been wondering about it too. Mine is near the brake booster and not very accessible. I'd like to use it, but all the croutons around here are squarish and obviously I'll need cylindrical ones with threaded holes in them so I can insert and remove them with a slide hammer shaft.

Never thought of heating croutons..

I've always used it to warm up pretzel sticks or those hard breadsticks..

If the motor in the blower is connected to + and - 12V, it should spin at the maximum speed for that blower motor/fan combination. This is equivalent to Fan speed 3.
By adding a resistance into the battery feed, less current is available to the blower motor and it cannot run as fast.
This is Fan speed 2.
Add more resistance in series and the motor spins slower still. Fan speed 1.

To control the fan, the 12v is supplied from the Ignition switch via a fuse, to the Fan speed switch. The wiring then goes to the "toaster" resistor bank and on to the blower motor.

So what is wrong with your fan?
Is there 12V on the ignition circuit? -
Is the fuse continuous?
Are the connections made properly?
Is the switch working properly?
Are the resistors in the "toaster" continuous?
Is the Fan motor working? (unplug it's connector and jumper 12V to it, it should run at fan speed 3.

HAVE FUN :)