Vehicle: 92 4DR S-10 Blazer / 4WD / 4.3 TBI

Problem: A/C blows out floor only no matter the mode or temp setting.

I was in the process of testing it, when the clutch went out on an already noisy compressor. So, it'll be down a couple of hours tomorrow while I fix all that good stuff.

Anyhow, I did replace a couple of cracked vacuum lines under the hood to no avail. I've got most of the dash out of it and all the doors that I can see seem to be working. I've got good vacuum to the two actuators in the center (1 for heater/defrost - 1 for ?).

I'm wanting to lean towards the lower actuator, but I'm unsure of how to check it. Can't really think of anything else.

Any help is appreciated.

Thanks,
Josh Hucks

 

Any ideas? this is mom's ride so I don't particularly want to keep it down for a while.

Thanks

 

Sorry for the late reply.

The image below will show you the vacuum schematic as well as a representation of how everything interacts in the system:


This sounds partially like you have a loss of vacuum supply to the HVAC controls. This is typically met with blower output being sent to only the floor and the defrost locations with a heavier concentration to the floor. This is due to the neutral (vent) positions of all of the actuators in the system.

 

I have good vacuum to the actuators though and I can see the one up near the middle panel vents actually move. WIll double check this afternoon.

Thanks a bunch

 

Just to update. Found the problem. A broken clip (?) attaching the lower actuator's threaded rod to the blend door.

Is this clip available seperately? Or is there a way to alternately attach it?

Thanks,
Josh Hucks

 

Could you snap a picture of the clip you are referring to and where it goes.

 

I'm also having this problem, except I get minimal flow out of the dash vents instead of none at all.. I also notice when I accelerate it takes what little air is coming from the dash vents away while the floor vents are blowing strong as can be.. that definatley tells me it's a vacuum problem right?

 

Yep! Definitely sounds like a vacuum issue.

 

That low actuator is a bitch and I guarantee that is the problem. I simply fastened a hacksaw blade to mine and run it out towards the passenger side. Whenever I want floor air I pull it to the right. Whenever I want defrost or AC in my face I push it towards the left. Good ****erRig sorry - Afro-enginneering because replacing that actuator is a major job.

 

to piggy back off of this topic....... great vacuum schematic btw....... where is the vacuum source located? exactly where does it enter the cab of the vehicle?