amplifier28

i have a 2000 Cavalier. A/C not blowing through front vents and blows through bottom of dash. is there a vacuum leak?

Jacfourteen

I had the same problem in my 97 z, the control knob had no effect on the air flow it always came out the bottom. I ended up finding a broken vac line in the engine compartment; it is a small black solid plastic line that runs from the the back side of the engine up around the brake booster then into the firewall. the line is really brittle and mine was cracked. I fixed it using some small heat shrink tubing. look at this first since it is easy to inspect. next place to look is the hvac controls, you have to pull the dash cover and the plastic trim panel then pull out the controls. then you can pull the vac lines off of the back and check for vacuum w/the car running. good luck!

__________________
99 Explorer (my daily driver)
-2" lift, 31" tires
-Magnaflow muffler
-7" Touch screen DVD stereo
-12" drop down LCD monitor
02 Mustang Convertible (wife's)
-K&N Filter
-Flowmaster 50
-7" Touch screen DVD stereo
68 GMC (project)
-300 HP 350

amplifier28

thanks! i will do that.

Jacfourteen

I know this is an old thread but, I wanted to give an update. At the time this seemed like a good solution, it kept the oe line intact and looked sanitary. well about a week ago the temp here got up to about 110 degrees, and the underhood temp got high enough that the heat shrink melted and the liquid goo got sucked into the vac line (not fun when the a/c goes out at these temps!). so I had to cut back far enough to find clear line (no goo) and cut it and then splice with some small rubber vac line that fit snugly over the old stuff. Just thought I'd let you guys know!

__________________
99 Explorer (my daily driver)
-2" lift, 31" tires
-Magnaflow muffler
-7" Touch screen DVD stereo
-12" drop down LCD monitor
02 Mustang Convertible (wife's)
-K&N Filter
-Flowmaster 50
-7" Touch screen DVD stereo
68 GMC (project)
-300 HP 350

tommyhorse

I know this is an old thread, but I just fixed my 2003 that had a similar problem with the HVAC control. It's a common problem - the control knob turns but you can't get air through the defroster or floor - only through the dashboard vents.

The problem is a cable that runs from the back of the control knob to a mechanical assembly inside the dash the directs the air floor to the different vents. The mechanical assembly is a plastic wheel moved by this cable. The plastic wheel in turn moves plastic levers that open and close various flaps that block or open vents. Over time these levers become hard to move - the surfaces get rough or their hinges dry out, needing a harder push by the cable to move. This puts stress on the cable that eventually gets a kink where it attaches to the control knob.

To fix this you need a new replacement cable you can buy from the parts counter at a Chevy dealer for $25. Then pay $90 to have it replaced. I did it myself - it required a lot of effort to see where the cable attached high up in the dash, then squeeze my hand up there to attach the cable. But the problem is, the cable will likely kink again unless you get those levers lubricated. I did that by using a white grease spray cans that had one of those tubes you attach to the nozzle. It was a tough job to get the can up there, but with persistence I did. I don't know if a mechanic at a dealership would go to that amount of effort.

So the fix cost me $25 plus tax and a Saturday afternoon.

But that's the fix. You can try to repair the cable by using pliers and straightening the kink in the cable. We tried that. But it's now a weak point in the cable and will kink again in a short time.

This is a royal pain in the ass to try to try to see what you have to do then get your hand up there to do it. But it's unsafe to drive around without a defroster and cold feet.

I've got photos if you need them.

Mark