Where do the heating vents on the dash go?

[Anonymous]

Any mechanics out there? I dropped something into the vent on the dash, and it fell down inside. Now there's a serious noise coming from under the hood, like something grinding or rubbing against something. It's intermittent but scary and serious sounding. What I dropped down the vent was plastic, but the sound is more metallic. Is there any chance what I dropped down there could be interfering with something major under the hood? It's probably a coincidence, but I know the vents must go up to the engine since that's where they get their heat. Any idea?

[Anonymous]

The vents go to a in-line fan, which controls the air speed in the vents. But the fan is usually pretty far down into the ducts, just past the heater core / AC exchanger / blend doors and just ahead of the directional air doors that divert air to the selected vents (dash, floor, windshield, mix).

They're VERY difficult to take apart (you usually have to remove the dash module) and its expensive because of the time involved.

You COULD try wrapping some duct tape sticky side out around a "flex-shaft grabber tool" (search it) and see if whatever you dropped will stick to it. It's a long shot, but I'd try it.

Also, get an endoscope camera tool (search it) and stick it down the vent and see if you can spot it.

[Anonymous]

Anonymous wrote:The vents go to a in-line fan, which controls the air speed in the vents. But the fan is usually pretty far down into the ducts, just past the heater core / AC exchanger / blend doors and just ahead of the directional air doors that divert air to the selected vents (dash, floor, windshield, mix).

They're VERY difficult to take apart (you usually have to remove the dash module) and its expensive because of the time involved.

You COULD try wrapping some duct tape sticky side out around a "flex-shaft grabber tool" (search it) and see if whatever you dropped will stick to it. It's a long shot, but I'd try it.

Also, get an endoscope camera tool (search it) and stick it down the vent and see if you can spot it.

Thank you very much! I'm going to try those suggestions. Do you think the thing can be clattering around on the fan and sounding like it's coming from under the hood? And is it dangerous to leave it down there? Thanks again!

[Anonymous]

The worst that could happen is that whatever is gets far enough in the vent duct that it jams up the fan. Which is bad, because if the fan stops, you got no defroster, no AC, etc. But it won't hurt the engine. It doesn't go anywhere near the engine.

But losing the fan is bad enough.

Bright side, the fan is easier to get to in most cases than somewhere in the middle of the ducts. It's usually at the bottom of the dash module, accessed from underneath. Depends on the car.