1998 gmc sonoma vacuum problem

[davew1]

I found the vacuum leak on the drivers side fender.There's a "t" there. One tube going down is the one that is shot.The other tube is about 6 inches long and is not connected to anything .Is that supposed to be open ?

[old_master]

There is a vacuum reservoir inside the left fender, just ahead of the hood hinge. There is one fitting on it.

[aa21830]

Reviving this thread...just went through vacuum/HVAC systems on both my '96 Sonoma and my '04 BlaZeR2. Both started with the "hiss of death" coming from behind the AC/heat controller on the dash, then loss of control of the air vents. Most people think it's just the controller unit and replace it, but the root cause is almost always transmission fluid in the vacuum lines (dry rot or other breaches in the vacuum lines are a distant second). This causes other problems that need to be looked at also

I did a complete write-up for the Sonoma, on how I cleaned up the vacuum lines and got m HVAC system working. A similar Blazer project is nearing its end; not nearly as much oil in the vacuum lines, actuators, and vacuum cannister and was much easier to examine the vacuum actuators behind the dash (did not have to drop the dash to access them). Here's a few highlights. These are somewhat large photos, so I didn't try to post them all here. Click on the links below....

Actuators behind glove box

Actuators under dash (driver's side)

Vacuum cannister under the hood

Space in the driver's side body that the vacuum cannister fits into (next to the anti-lock brake motor/booster)

Brackets around the anti-lock brake stuff that I had to remove to pull out the vacuum cannister (to check for oil inside)

Looks like I'll only have to replace the transfer case vacuum switch and the AC/heat controller unit on the Blazer. The actuators and vacuum cannister all tested fine. Much easier job on the Blazer than the Sonoma.

[rprough]

Nice pictures, very clear. Good photos allways help.