Another Vacuum Line Question.

[millerwl71]

I did everything I could think of to fix the weak air flow from my vents. Or should I say the air is coming out from everywhere instead of where I tell it to blow out of and it's very weak. Anyways, I put a new check valve, new lines, and the ball seems to be in good condition. I pulled the lines off the check valve that are suppose to go to the HVAC and behind the plenum. The one that goes behind the plenum has alot of vaccuum but the one going to HVAC dosen't have any. Don't know if it suppose to. If that line is bad, where does the line go once it hits the fire wall? I search the threads and found that everyone has something to do with the check valve or the vaccum ball. Any other Ideas. It's driving me crazy!

[Supreme Cutlass]

Those plastic lines have a big tendancy to break, take off the plenum and check the lines.

[millerwl71]

92' Z34

I have really good vacuum. My cruise works but still little air pressure coming into car from any setting.

Could the unit just be bad, or the blower motor? It turns on and sounds good. BUt in the lowest setting the blower really dosent sound like it's on at all, but it is barely. I have to put it at its highest setting for it to blow at least a little air out. Is there a vacuum line that runs to the HVAC controls that I might have to check?

 

Thanks

 

[slick]

The biggest vacuum line problem I had with my Z34 was the lines right behind the the plenum. The space between the plenum and firewall is where they kept coming undone for me.

 

But, does it come out of the vents you select, or just the defroster vent at the top of the dash?

[millerwl71]

It seems to come out of the vents I select. Well I should say yeah they do. It seems to have the most pressure( and it's not a lot) out of the vents then the defrost or the feet.

[slick]

Well, since you have the most pressure at defrost or feet, it is a vacuum problem. Your going to want to recheck all of your lines again, unfortunately.

[millerwl71]

No, I have the most pressure at the vents that blow in the face . And it does change when I switch it to a different setting. It will stop blowing out of the vents and blow out of where ever I put it to. Just not the same amount of pressure as the vent, that blows in your face.

[slick]

Oh ok, I misread that then.

 

Blower may be going out? I'm not sure on this one.

[DiscoStudd]

If you can get the "mode" to change, then it's not a vacuum problem. It sounds like you have an airflow problem. What you'll need to do is clean off the fins of the evaporator core (actually quite a common problem on GM's.)

 

Since the blower fan is under the dash, you're going to have a bitch of a time reaching up into the airbox to get to the evaporator core. I'd suggest throwing some soapy water into a "garden sprayer" and spraying it up towards the evap core (make sure you lay some towels down on the carpet to catch any water that drips back into the cabin.) If you can reach a toothbrush up there, try and lightly scrub the evap core once you've saturated it with the soapy water.