The A/C system compressor operates when in the defrost mode. If the noise is also heard when running the A?C it is more than likely a problem with the compressor/pulley.
was there something on your dash that fell in the vent, a bad fan will make noise all the time.
Alternator straining to maintain battery charge?
Engine running hotter then 220 degrees can cause valvetrain noise. Bad fuel can also cause valve noise / PINGING sound. Ignition timing to high / Advanced to far, can also cause engine noise.
A bad harmonic balancer can cause a knocking noise. The harmonic balancer doesn't actually produce the noise, but it can cause the noise in the engine.
There are pages and pages and items that can cause a check engine light. You need to have it checked for codes with a scan tool. After repair light can be shut off with scan tool.
It is probably your cooling fans. These are electric and may run with the engine turned off. It is probably your cooling fans. These are electric and may run with the engine turned off.
No
cold engine
Several things could be making the Lumina growl. Check the belts and pulleys on the front of the engine. Check the engine mounts as well. Either of these areas can cause the problem of the growling noise.
check a/c compressor and belt.
A bad compressor belt can cause a whistling noise while running the air conditioner. A bad engine can also cause this noise.
Your fridge may be making noise due to the compressor running, the fan motor operating, or the defrost cycle activating. These are normal functions of a refrigerator and should not cause concern unless the noise is unusually loud or persistent.