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Old 08-08-2001, 05:03 PM
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MBenzNL MBenzNL is offline
Join Date: Jan 2001
Location: the Netherlands
Posts: 1,417
Originally posted by 1994C220
As far as the vacuum pump in the trunk, I can hear the one for the power door locks....and it buzzes constantly...when the car is on....
That is the one!!! And that is your problem!!!
If the vacuum pump is constantly buzzing, you have a vacuum leak in your AC system.
The vacuum pump in the trunk has 2 outlets; 1 for the central doorlock and 1 for the AC controls.
If I were you, I started in the trunk. If the AC vacuum line is connected to the engine's vacuum, the pump in the trunk still gets commands from the AC because of the faulty set vacuum valves...

Start by finding out where the AC vacuum is connected to and then start searching for a leak.

good lick & greetingz,
1990 300SL-24
1993 C250D
with a minor 600+k kilometer
(the Netherlands)
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