HVAC problem

[Thewolf]

Hey guys, I have a 2000 alero with the 3400 engine. When I just start the car and put on the A/C on the highest setting it blows the air hard though the vents. Then if I turn down the fan setting to 2 and try to turn it up again to high setting, I could hear the blower increasing speed but it doesn't blow hard through the vents. It seems like if something is blocking the vents. I've even tried the heat setting and it still blows the same way through the vents.

I've replaced the blower motor resistor with an aftermarket one, not the ACDelco one from GM. Could it be the resistor overheating and going into protect mode?

Even if I turn off the car and start it again it still does the same thing.

Btw, my temperature gauge is at (or around) half mark when it does this.

[foxsdaddy67]

sounds like a vacuum line problem on the back of the controls almost to me

[MMGT1]

I would start where fox is suggesting

[foxsdaddy67]

yeah cuz even when i got it on the dash vents mine sounds like its blowing out the defrosters too, im gonna have to do some looking on mine since i was screwing around with my stereo the other day and it wasnt doing that before that

[Redog]

Yeah I agree, the vacuum line is off somewhere.

I would check under the hood first, if you have the V6, the vacuum line for the HVAC contorls is the gray line that goes into the manifold in front of the throttle body

[zzyzzx]

Ummm, when resistors overheat they go up in smoke (literally).

[Thewolf]

Originally Posted by foxsdaddy67

sounds like a vacuum line problem on the back of the controls almost to me

Ok, I'll check it out when I put in my new HU.

[AleroB888]

Ok, here we go,

is there a main vacuum line going to this thing?? we need a diagram of some sort....