i got on shoebox's site and read up on this but....when i pulled the vacuum check valve up to where i could get to it none of the lines seemed to be leaking. coudnt push air through the mode selector line, and couldnt push air through the line goin to the vacuum tank. no leaks in the line to the intake either. pulled the vacuum check valve out and it didnt have any cracks or anything. mode selector and vacuum tank connections flowed freely and the end going to the intake only flowed toward the intake. any more ideas why my vents arent working rt? anything im missing?

 

anybody? whats my next step?

 

Your symptoms say lo/no vacuum to the dash valve assembly. Ya really need a hand held vacuum pump like a Mityvac or equivalent that has a vac gauge attached. Stick it on the line at the check valve to the dash in this diagram http://shbox.com/1/hvac_vacuum.jpg and see if the line holds vacuum when pumped up. (no openings in lines or valve assembly in dash). If you just have a vac gauge only you can also start engine to verify vacuum is present in line w/engine running and stays there a while (reserve tank) after stopping engine. Could be a loose connection, cracked line at control valve in dash or open somewhere between.

 

k i disconnected the intake vac line from the vac check valve and connected a vacuum pump. i can draw vacuum on it but it DOES leak down after just a couple minutes. the needle seems to drop maybe like twice as fast as the minute hand on a clock. is that losing vac too fast? seems like that would be enough vac to work to me but i dont know.

 

From what you say vac there for a couple on mins should work, but you still have a leak. Slow leaks, no reserve tank vac, usually only show at low vac conditions (acceleration) and usually work fine at idle. I just tested mine w/hand pump..... Pulled vac line off the intake manifold and installed a hand pump w/guage on that line to the check valve assembly. Pumped to 20 in/hg and it only dropped 3 in/hg (20 to 17) after 20 mins. I then activated a different setting on dash switch (defrost,floor.vent) the gauge drops 5-10 in/hg, when switching on different actuators, but when pumped backup holds vac to the system and each of the activated vacuum actuators with a very slow drop over mins (no visible needle movement when looking at gauge). You should work back from the check valve connections, and isolate either the line to and/or reserve tank side or the line to and/or the dash switch side of the system. Then keep on moving back to the leak. Could also be a leaking actuator, does it loose vac in all switch positions ? If reserve tank is leaking then I would thing it would take an awful lot of hand pumping to get to 20 in/hg, unless you are using an electric vac pump.

 

thanks bob for your help. i figured out what the problem was just a few minutes ago. It dawned on me that I never checked the vacuum from the actual engine. DUH! i didnt check the vac before i did this but i took a piece of wire and snaked it thru the side of the intake then connected all the vac lines, fired up the motor and wallah! all the settings on the mode selector worked like a charm. it must have had carbon build up or something inside the intake i guess. thanks again buddy