What is the little box below the dashboard on the passengers side

Hi can anybody tell me what the little devices that sits on a plastic pipe which goes to the heater matrix and what is it's purpose? My one is leaking

Do you have picture? Or maybe can you point it out on a diagram from RealOEM?
http://www.realoem.com/bmw/enUS/partgrp?id=1413-USA-01-1989-E30-BMW-325i&mg=64

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Dave
'91 325iX

Quote
Mark angel
Hi can anybody tell me what the little devices that sits on a plastic pipe which goes to the heater matrix and what is it's purpose? My one is leaking

It is on one of the two pipes leading to the heater core?

#16 in this image? [www.realoem.com]
or #7 in this one? [www.realoem.com]

If so, it's a solenoid valve that opens or closes to allow/prevent hot coolant flowing through the heater core.

With the heater control dial turned to full cold, and the ignition switch in the run position, the solenoid valve is energized to hold that valve in the closed position.

With the ignition in the run position, as you turn the heater control dial more than 20° away from the full cold position, power to the solenoid is switched off and the valve will spring open to allow hot coolant to flow through the heater core.

If you turn everything else off in the car, noisy blower fan etc, turn the ignition key to the run position, then adjust the heater control dial more than 20° from full cold and back, you should be able to hear the solenoid valve thunk open or closed.