My vent air flow drops off when I'm accelerating ?

[mfewtrail]

WAIT! the newer cars use a different valve than the older cars. I've seen a "Help" part that appears to be the same as the older cars, but not the newer cars...

 

I was assuming they were all the same valves w/ three connections. What's the difference on the newer ones? I know up until 1994ish appears to be the same from what I remember. After that year model, I haven't seen a check valve in a while, so I couldn't say..

[White93z34]

I've replaced that dumb valve already. Hell Shaun and myself have on our z34s both still do it bad.

[chrisflstf]

Autozone does carry the vacuum valve $3.99 - p/n 47150, but they dont look like mine exactly. Little larger and all black. It says its for GM cars. Went to Napa and they have the exact replacement. Its called a Heater Door Vacuum Switch - $10.79. It will be here tues.

 

Hopefully this will fix mine. I put a load on the vacuum reservoir (aka Org of Power) with a vacuum pump and it holds fine. Takes a while to suck all the air out. All the hose connections are good. Small ty-wraps work well to tighten things up:dance:

[digitaloutsider]

The vacuum check valves are extremely generic. I've yet to see anything different about them when it comes to the way they function.

 

My TGP does this with all new check valves and a known good ORB OF POWER. My Z34 does it as well, yet you can sometimes hear an almost hissing sound coming from under the dash whenever it happens. I'm willing to bet one of the vacuum lines on the distribution block gets brittle and shitty and starts leaking.

[chrisflstf]

Fixed my problem today. My vacuum valve was bad. It was easy to confirm with a hand held vacuum pump. The old one had a leak. New one tested fine. Still had another leak though. I found a break in the hard line between the Orb of Power and vacuum valve. The vacuum line rubbed on the corner of the battery and wore through. Short section of of hose fixed it good. Now I have full AC and can stand on the pedal too:lol:

[Highmilagecutlass]

Thanks Chris

whats the part number for that valve ? and where can I get one at?

 

Thanks again !!

 

Shawn:)

[chrisflstf]

Got mine at Napa. P/N 207449

 

Pic of the old valve and new part box. Black end goes to the intake manifold

[Highmilagecutlass]

Got mine at Napa. P/N 207449

 

Pic of the old valve and new part box. Black end goes to the intake manifold

 

Thanks Again !

Nice picture

[Crazy K]

93- and 94+ are different... 94 lumina might be 93-?

 

if you have hissing under the dash, it is probably not the colored vacuum lines going to all the actuators... they do not go brittle and seem to be made of silicone... You could have a actuator with a vacuum leak, or your vacuum switching box is leaking...

[chrisflstf]

Easiest way to fix pneumatic problems like this is with a hand held vacuum pump. Only takes a few minutes and gives honest, accurate results. If you connect it up and cant pull and hold vacuum, you have a leak.

[Highmilagecutlass]

93- and 94+ are different... 94 lumina might be 93-?

 

if you have hissing under the dash, it is probably not the colored vacuum lines going to all the actuators... they do not go brittle and seem to be made of silicone... You could have a actuator with a vacuum leak, or your vacuum switching box is leaking...

Thanks Ken !

I will check it out.

[Highmilagecutlass]

Okay , Here's an update

I pulled my battery out yesterday and there it was , the vacuum line the ORB of power was cracked and split two. So I patched it with a piece of rubber hose.

Thanks to everyone who tried to help me:thumbsup:

[94vertluvr]

Ken - hey i don't know if i have a similar problem; my AC doesn't work at this point but when I drive it with the heater/blower in the off position (have the electronic switch heater for the 94 verts) and the engine warms pretty good I get a LOT of heat that feels like it comes right up under the steering column. Is this a related issue or something totally different? Thanks!

 

93- and 94+ are different... 94 lumina might be 93-?

 

if you have hissing under the dash, it is probably not the colored vacuum lines going to all the actuators... they do not go brittle and seem to be made of silicone... You could have a actuator with a vacuum leak, or your vacuum switching box is leaking...