I cant get any air whether cold or hot blow from my main vents on my dashboard in my car?

Question

I have a 99 monte carlo and whenever i turn on my heat or ac on it only blows from the vents that hit my feet and the vents by the front widow that defrost the windows. It will not blow from the main vents on the front dash does anybody no my problem or how i can fix this please, thank you

Answer 1

When you switch the knob to the main vents, a butterfly valve flops over to redirect the air.

One of three things: the butterfly valve is stuck, the vent hose is disconnected, or the switch assemble is faulty.

Most likely it's the valve or the hose. Crawl under the dash and locate the thick black hose that carries the air to the vents. Trace it back to the major junction, and see if the hose needs to be reattached. Open it up and work the butterfly valve gently until you free it up.

Last resort, tear down the controller assemble and correct the fault.

Answer 2

Does it sound like you have a vacuum leak in behind the dash? The vacuum switch in the AC / heater control assembly has come apart. There is a plastic button with two short legs that pops off a foot and the vacuum wafer switch comes apart. I'd like to find some of those buttons - else do what dad and I did - two small washers, a short,short, tiny bolt and a self locking nut.
Also check to see that there is no leak in a hose to a small, round vacuum chamber under the hood - this stores a bit of vacuum so it won't switch back to defrost during acceleration.
Do you put stuff up on the dash that has disappeared? It can go down the defrost duct and wedge the door open. That means going under the dash and taking the ducts apart -starting with the ones that blow on the floor.

Answer 3

There are vacuum hoses one way valves behind the battery passengers side that send vacuum to the dash vent control vac motors check that first. Location may vary but most the time it is that black valve in the plastic vacuum tubing.