daytonabeach

I have a W210 SW 1996, on the side of the rear fusebox (under backseat) there are a large black plastic box with a grey thin hose attached to it, apart from that the grey hose is disconnected, and the hose is plugged in with a screw instead.

What is it, and why do you think it has been disconnected?

Hirnbeiss

There should be a vacuum pump there next to the battery, and it's job is to operate the door locks via the vacuum hoses. The only other hose there is a vent hose on the battery that should drain through a grommet in the floor.

loubapache

It sounds like it is the PSE (Pneumatic System Equipment) module.

Does central locking/unlocking work on your car?

My guess is that one particular device (e.g. the fuel filler door, just as an example) has a leak so someone disconnected that hose and plugged up with a screw.

daytonabeach

Sounds more like it.
So, that means if the hose to the fuel filler have a leak i wont be able to open that, if its connected?
When its disconnected, it also never locks with the doors then?
So, when i have locked the doors, the fule filler should remain open, if not, theres some other reason, right?

Yes, central locking works fine...

loubapache

The fuel filler is just one example I used. The PSE also control trunk, multi-contour seats and a variety of other vacuum devices when the engine is not running.

You said you have a 1996 but a SW (station wagon?).

If there is a leak and the hose is still connected, then the worst case is that pump can run all the time and get burned out.

I suggest you check everything out to see if there is anything that is not working with that disconnected hose.

daytonabeach

Should have checked before i answered

Fuel filler also locks with the doors, so what other thant doors and fuel filler are it for then?

daytonabeach

Edit: contour seats works, trunk works, yes its a station wagon...
Cant think of any other stuff controlled by vacum...
But there are only one grey hose coming in to the box, and the box seems airtight and have no other port or intake :S

loubapache

The trunk or tailgate. Seats (if you have fancy options like lumbar etc).

Then there are all these vacuum devices in the climate control system. They also rely on this pump when the engine is not running.

Try to see if there is any identification on the unplugged hose.

daytonabeach

Hey, thanks for all the suggestions, ill try to take a picture of it and post it here...

loubapache

This is not an exhaustive test but try the REST button on the climate control panel and remove the key (after the car being driven and coolant warm). Sounds like you are in Hot Florida so do this in a cool morning or evening. Then see if you have the heat (aux water pump) working and blow warm air into the car.

daytonabeach

Hehe, im actually in cold Norway

Whats the REST button?

When rolling the temp wheel to red it heats or blow hot air in cold days if thats what you meant?

loubapache

That is why I ask about station wagon because we do not get the wagon in 1996 here in the USA.

Then if everything is working, it could (although very unlikely) it is for some option your wagon does not have but the pump had a connector build for it.

Then you may not have the REST button as it is part of the automatic climate control system (all W210 sold here in the USA has auto CC). Basically, the REST uses the coolant heat to heatthe car with engine OFF, kind like a residual heating. With the engine off, the car has no vacuum but the PSE pump.

daytonabeach

I have the EC button, which turns OF the AC when lit...

The plugged hose doesnt seem like its done prof, its screwed in with a philips grip screw...

Hmm, im deadly curious on why its like that :-/

ohlord

If you are not the original owner then someone in the cars past had a water issue or a failure issue with the PSE Control Module - A37 pneumatic system equipment.They swapped in a unit from another car with different options and plugged the no longer needed line.
Sleep well

daytonabeach

Aiii see, dont fix whats not broken then

ohlord

and Yup
If these all work. Best to let sleeping dogs lie.

loubapache

Back to the REST button feature. Does your climate control look like the picture below? (See the REST button?) If not, then you do not have that feature. Many cars sold outside the USA have manual climate control. We only get auto CC, no choice.