Hey does anyone know what this pump is for? The small black airlines that come off the bulb-looking thing are broken and I can't seem to figure out where they are supposed to go? This is located in the front panel access area of my 1995 U300.
Thanks in advance!
That's a vacuum pump for the dash heat and a/c. The round thing is a vacuum reservoir.
It should run periodically when the ignition is on. When enough vacuum is attained a vacuum switch will shut it off until the vacuum level gets too low again.
Any chance you know how this should be routed? The small vacuum lines have disintegrated and I have no idea where they originally ran to.
See if the photos below help any. Routing is basically out from pump, into reservoir, and out of reservoir to a "T". From the "T" one line goes to vacuum switch - the other line goes up to dashboard A/C-heater control panel. The vacuum switch controls the relay that turns power ON and OFF to pump.
BE CAREFUL MESSING WITH THE VACUUM SWITCH. If you break it, a replacement is very hard to find.
NOTE: Pencil drawing - wiring corrected
The vacuum pressure switch controls a relay mounted on the firewall nearby. The relay gets power from a fuse under the lift-up dash cover. The relay sends power to the vacuum pump. The ignition switch must be ON for pump (fuse) to receive power.
See B-2037 12V Wiring Diagram.