I hear a vacuum leak behind my heater / ac control. Is there something in there that has a vacuum line? What should I look for to troubleshoot?

 

when i took out my stock heater controls too make a gauge pod, i never looked at the wiring etc. theres a vacuum hose that runs off the rear of the intake manifold that runs into the back of the control unit for what i dunno but i had to plug mine off cause it was leaking...hope it helps man

 

The slider that control which vents are in use, uses engine vacuum to control the vacuum servos that adjust the airbox. If you pull the heater/ air conditioner panel you will find a clear silicone block with several vacuum lines connected to slider. Make sure the plastic vacuum lines are not cracked, and also make sure the silicone block thing is fully seated.

 

Everything he said above me is true. Is it a leak though, or do you hear it hiss then go away? Or is it a constant hiss on certian levels like vent or bi level or Defrost?

 

It is consistant, it starts when I start the car, continues no matter what setting the slider is at, and when the car is shut off, it keeps going for a little while till the vacuum runs out.

 

You have a leak, and if you use your vent, heat, A/C or Defrost don't delete the vacuum line, just pull apart the bezel around the dash right there. I think it's a t10 or 15 torx head, or something close to that. Pull the bezel, then unscrew the HVAC unit, and check all of the vacuum lines behind it, it'll be fairly easy to find out which one is leaking.