Hey all. '91 S10 Blazer 4 door, been going through my HVAC lately. Mostly everything works all right, except when the fan's on it blows out the floor vent in every switch position. The dash vents, circulation and defrost vents all open and close like they should, it's just the floor vent. I figure it's probably a vacuum line or something but I've got no clue where to start. Anyone dealt with this before?

 

the floor vent is natrually open, it relies on a vacuum accuator to close it. Im thinking the actuator or line to it is leaking

 

Where is the actuator located? Is there a diagram for which line goes where? I can't find anything on google.

 

Okay after some searching, I found a thread where swartlkk posted some charts, it looks like they're exactly what I need, but I can't get the full-size images to open, when I click them it just pops the thumbnail up again. If anybody has those charts I would be so grateful if you'd post them here, because I can't find them on google or anything.

Thread here: under dash vacuum lines - Blazer Forum - Chevy Blazer Forums

 

Found one of them:


Valve 9 is what I'm after. I looked at it, it has 2 vacuum lines going to it, one all black, one black with a blue stripe. The black one has vacuum with the switch in the OFF and HEATER positions, no vacuum in the others. Blue stripe has vacuum in MAX A/C, A/C, VENT and DEFROST. Can anyone confirm whether those are right? If so, I've probably got a bad actuator. Don't hear any hissing except when moving between switch positions.

Still looking for the full size version of this image:

 

Alright so I've been busy the last few months, but I did wind up getting a replacement actuator. Went to fiddle with the old and it broke off the box, which is annoying. The old one is definitely toast, though.

So now my question is, how do I install the new one? It looks like I have to remove the floor duct to get it apart, what's the best way to get it apart?

 

idk, i havent taken mine out. I need too but havent... I just have capped the vacuum line to it and just have it default to floor and defrost. I dont have AC working anyway, lol

 

Where did you find your replacement actuator? Mine is bad in my 1993 S10 4.3 TBI.