When I first start my car up in the morning there is a whistling sound coming from the engine. It will whistle for about 15-20 seconds then what sounds like air being released follows the whistle then the car sounds fine. It will do this every morning or whenever it has been sitting for an hour or so.

I took this issue to the dealership, and from what they told me, the air pump is broken and there is possibly an air pocket. Can anybody help me find out what they mean by an "air pump", and what it does, where it is located, and could this be my issue?

P.S.. Chevy couldn't fix this problem under warranty due to an accident i guess... Never new this was in an accident.
Check engine light is not on

Also when i bought this car the weather gauge on the dash shows two dashes instead of the weather, chevy also told me this was broken to. Can somebody help me with this problem to?

Thanks

 

The air pump is part of the secondary air injection system. When the engine is cold and the car is started, the secondary air valve opens and the air pump pumps air through the valve and into your exhaust. It operates for 30 - 60 seconds immediately after startup, then shuts off. This supposedly improves the operation of the catalytic converter while the converter is cold.
On my 2006 Cobalt, the air pump is located directly behind the bottom of the radiator. A hose runs from the air filter housing down to the air pump, then a second hose runs around the other side of the engine up to the back of the engine to the air valve, which is mounted on top of the exhaust manifold.
If you have a leak in the hoses, that could be causing the whistling sound, or it might be the bearings on the air pump. The air pump costs $200 through Chevy.