on my 95 S10, the dash vents will no longer blow air out of them when you switch it to the vent position. this problem just started yesterday. now it doesn't matter if its hot or cold air, it just blows on the floor only. the blower motor works fine and so does the speed of the blower motor. whats wrong? why can i no longer get it to switcg positions from the floor to the dash vents?

 

You could have a vacuum supply problem to the HVAC control head. That is where I would start looking.

Does your 4wd work?

 

its a vacuum line.
mine had the same problem until yesterday.
would only blow in the defroster setting. blower worked fine as well as the speed.
found a hole in one of the lines and now it works fine. and i have my 4x4 back

 

Look for the "t" in the vac line behind the abs under the hood. Remove it and blow through it, might be clogged. Also check vac lines for holes/pores. My "t" was clogged with dirt, but it all came from a problem with tranny fluid in my vac lines. Faulty output shaft seal.

 

Check that vac cannister on the fender well for holes, if you find one put some silicone on it.

 

i had that same problem when i bought mine. There is a vaccum ball mounted to the underside of the hood and the line on mine was dry rotted. i replaced the line going to the ball and to the T that fixed it for me and got my 4x4 working again.

 

Interestingly I have a similar problem, except my 4x4 works.

Would it still be vacuum related?

 

It probably is only I would check the actuator under the dash. There are check valves in the system that might help isolate the leak. The best tools for troubleshooting this stuff is a hand held vacuum pump (like a Mity-Vac) and a manual with a vacuum schematic

 

update: ok i found my problem and it was my fault. i forgot to hook back the vacuum line behind the CPI intake when i worked on the distributor...i hooked the line back up and now the vents works. thanks guys for your advice. thats what made me look back there...

 

We have an honest man at least.