Thump Thump Thump

[ZZvroom]

2003 GT

Was just at the car testing the automagic headlights. When I turn on the ignition, there is a thump about once a second coming from inside the dash in front of the radio or glove box. It continues after starting the car.

It's not the HVAC fan; I tried changing its speed, etc.

What is in there that might be doing this?

[tpollauf]

Sounds like your air circulation actuator. Visit this recent thread for more info ...... viewtopic.php?f=11&t=47147&p=526356&hil ... or#p526356

[ZZvroom]

Thank. That sounds likely.

Have to wonder why they used electric vs. vacuum power for the air doors.

[Bookworm]

Thank. That sounds likely.

Have to wonder why they used electric vs. vacuum power for the air doors.

_That's_ not the wonder. The wonder is why they didn't use a pressure sensor to keep from snapping the gears, or at least use metal gears.

[SeattleJeremy]

Thank. That sounds likely.

Have to wonder why they used electric vs. vacuum power for the air doors.

_That's_ not the wonder. The wonder is why they didn't use a pressure sensor to keep from snapping the gears, or at least use metal gears.

Money and weight. Pressure sensors and metal gears are more expensive and heavier than electric switches and plastic gears. Vacuum stuff is also more expensive, heavier, and more prone to failure than electric stuff.

[jolt]

It is the weakest part in the chain kind of thing. Something will break, it is just what part do you want to replace.... and the cost of it too. The cheapest and possibly the most reliable is to use a cable from the control to the damper door. Of coarse you get no automatic controls with this setup but it provide itself very reliable in the cars of the '60 and '70.