98 Blazer climate control,vacuum bundle

[tigerhwk]

I've been searching the board and cannot find this info
Where is the vacuum bundle for the climate control,AUTO,located under the dash and where does the MAIN vacuum get it's source.
I cannot locate it outside the firewall and cannot see the vacuum canister if it has one
Thanks

[MT-2500]

It is a black vacuum hose from engine to the back of ac/heater control panel switch.

To check at control panel you may have to pull control panel out of dash.

Check all rubber and plastic vacuum lines off of engine intake.
Some have a heater vacuum line on drivers side of intake below TBI. that feeds into the vacuum tank and into firewall to heater controls.

Look for a vacuum reserve tank sometimes hid in fender area..
Some use hard black plastic lines that have a habit of breaking.

What is yours doing or not doing?
Good Luck

[tigerhwk]

I'm getting no movement at all from the directional control,stays on vent and doesn't make so much as an effort to move when turning the dial.
want to check for vacuum at source.
All lines under the dash look tight.
Could the dial switch be bad and how can that be tested as well??

I replaced the intake gaskets this summer and want to find out if the vacuum line was damaged but can't find it beyond the firewall entry point

[MT-2500]

If auto-matic ac/heater controls a good havc capable scanner is required to test it out .

A good vacuum gauge will test for vacuum to and threw the solenoid assembley.


Did it quit when gaskets were replaced or before or after.

If you have good vacuum to firewall then look for the vacuum solenoid assembley and see if vacuum is geting to it and threw it.
Remove the under dash hush panel and.
It should be on the center of heater housing under dash with wires and vacuum line to it.
Good luck
MT

[tigerhwk]

It didn't work well last year either,but enough to defrost the windsheild.
Won't even move to defrost or floor this year

[MT-2500]

They are vacuum and elecronic controled.

Make sure you have good vacuum and if so then check the electronic controls for a problem.
A havc engine body capable scanner will be needed to test it out .
If any codes post back code no.
Good luck.
MT

[tigerhwk]

Pulled the coupler apart inside firewall and heard the vacuum release so I believe I'm getting vacuum,
Dial switch or multi vac switch bad??
How can you tell,Where would I take the control panel to be tested??

[MT-2500]

As in post 6 it is scanner time.
Post back any codes.
MT

[MT-2500]

When testing for vacuum it is best to use a vacuum gauge and make sure you have good vacuum equal to engine vacuum around 18-20.
Most parts places sell them for 10$ range.
One of my first and best testing tool that can tell you a lot about engine running and other problems.
Good luck
MT