mkviii Electronics Air compressor??

[MKVIIILSC]

It's not the one for the suspension. This one is located on the driver side way up front and under the battery and headlight.
Mine sounds like a thrashing machine. It starts with the engine and runs for about a minute and shuts off. Then it cycles again when the vehicle comes to a stop.
Of course it goes away when unplugged. But I left it plugged in to know when it ultimately fails.
What does this thing do?? Is it a necessary system component?
My metro doesn't have one of these.

 

[billcu]

What year is your car, if it's 96 or newer it could be the secondary air Injection system which blows air into the exhaust at start up for air pollution control. It shouldn't run when the vehicle comes to a stop, I've noticed the radiator fan on my 97 and 98 turns on when I come to a stop though (my gen 1's don't do that).

Edit: I see now that you have a 97, it's good to put the year in your question posts, as each year has their own little differences.

 

[tixer]

Based on your description of the sound, it could be the suspension compressor after all. The suspension compressors are known for wearing out the rubber isolation grommets between the compressor and the mounting bracket. When that happens, they get mighty noisy. It's not too tough to swap them out if you find that's the problem.

If it is the the secondary air injection pump, I'd say that one is safe to disconnect, particularly if you don't have emissions testing in your area. I've never heard one fail, but I do remember mine humming away for a minute or so when I started the engine.

I think I'd be tempted to unplug it, and see if it triggers any dash lights. If it is the Air Suspension compressor, you'll get "check air ride" on the display. You'll know what you've done..

 

[MKVIIILSC]

It's a '97.
Well it's the wrong side of the car for the suspension compressor. (been replaced) But I do like the "unplug it" idea now. I've already been thru the DEQ clean air station and passed that test.
Another reason I like that idea: $300. O'Reilys.
It really needs to go up on the lift for this. Access is much easier.
We'll see if it throws a code. If not I'll plug it back in a couple years down the road.
Thanks for the replies. I will report back.