Dash HVAC Controls not working... No Vacuum!!

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travelinlite

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Aug 9, 2015
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38
So when I bought my '94 Vectra, I knew the dash air was not working and controls were "stuck" on defrost. When I pulled the dash apart I noticed the lines all looked good but were not getting any vacuum. I traced the vacuum hoses under the hood to the "vacuum ball" which looks to have two hoses connected. These hoses run under the coach to a contraption above the front axle that has air hoses running into it, which I believe from research is a "venturi style vacuum pump"

The bottom hose that is not connected constantly bleed air out (and will drain my air tanks sitting over night). The upper side hose has pressure, but I don't feel any vacuum from the lower hose.

Before I start digging into it, anyone shed light on how this thing is supposed to work??


Edit by staff - changed message to topic solved
 

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Are you gas or diesel?  That "ball" is your vacuum reservoir.  Your description of the system sounds like a complicated way to generate a vacuum.  I would simplify things and install a 12V vacuum pump - a good Hella is about $80.  Let me know if you want to go this route and I'll get a part number for you.
 
Diesel... I agree about the complicated part!

In my research it seems most coaches have a black box type unit under the hood that have 12v running to it and one air line. I'd be fine replacing this with an electric unit if there is a simple conversion
 
That's a good chassis manufacturer. I would contact Spartan - they might be able to furnish you with some schematics of how all that is supposed to be connected.
 
pulled the mechanical pump off and tried to blow air through it... no vacuum. No way to disassemble, so i ran some contact cleaner though it  and let it soak for about an hour and Shazamm!! Put it back on and we have vacuum now. Apparently something was plugging up the internal ports. Now all my vent controls work, but still no heat or AC working...

on to the next item on the 20yr Old RV punchlist...
 
Good show!  After you get all systems working, you will have good familiarity with your rig.  We bought a 10 year-old ketch (sailboat) years ago and over a period of four or five years I completely redid the electrical, plumbing, engine cooling and running/standing rigging.  When we went cruising in the eastern Caribbean I had very few problems to deal with and when something happened, I knew where to start troubleshooting.
 

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