the ball is used to basically store excess vacuum, kinda like a vacuum booster....when you lose vacuum to your air vents they automatically default to floor and defrost. is the hose plugged into the ball? does the ball have cracks or anything?

 

I thought to checked for that...the line was plugged in, and there did not appear to be any damage to the ball.

 

And a bump for this...

Took off the ball under the hood and double checked for any cracks, and could not find any.

Still trying to find any vacuum lines that might be unplugged or clogged, but still cant find them. Any ideas where I need to be looking to find the vacuum lines behind the dash that would control the flow of air between the floor/vents/defrost?

 

trace the vacuum hose that hooks into the ball..that might lead you to it.

 

Thought of that as well. Pulled the cover above the pedals on the driver side, where the wires look to be coming through the firewall, but could not find the vacuum line. Unless there is another point... idk. Where do all the vacuum lines that control the air flow end at? I could start there then work backwards!

 

Having this same problem with my 98 blazer except mine won't switch from vents to defrost or anything just stays on vents. Could this be my problem or should I look elsewhere. I've had the bezel, glovebox, and all underneath dash plastics off and checked all the vacuum lines all seem to be plugged up and working normal. Also could the climate control its self be the problem? Going to check real quick on the ball your talking about. Thanks in advance

 

there is also the check valve inline near the ball if it is bad you will have this issue its a one way valve and if it is stuck open its bad, to check it pull it off blow in one end then suck you shouldn't be able to do one ( blow or suck ) if you can do both it is bad and it wouldn't hurt to just replace the ball the internals could be bad or there could be a pin hole ... never know

 

MachNU: likely problem is the vacuum actuator that switches AC air flow to the dash vents; my '95 had a torn diapharm. I had to replace the heater core so that is when I found it...when I had the dash completely out.

You might be able to remove all the lower trim panels and get a hand on it. Located above center floor console, between HVAC controls and radio. Might be able to remove HVAC controls and radio to get access....have no idea as I no longer have a '95.

Good luck.