2011 Chevrolet Volt Owner's Manual - Page 300

8-8 Climate Controls Notice: Do not try to clear frost or other material from the inside of the front windshield and rear window with a razor blade or anything else that is sharp. This may damage the rear window defogger grid and affect the radio's ability to pick up stations clearly. The repairs wouldn't be covered by the vehicle warranty. Remote Start: For vehicles with this feature, the climate control system may be started by using the Remote Keyless Entry (RKE) transmitter. The climate control system will default to an appropriate heating or cooling mode. See Remote Start on page 2‑8. The rear window defogger turns on if it is cold outside. Rear Window Defogger Compressor The vehicle has an electric powered air conditioning compressor. This allows for continuous air conditioning and/or high voltage battery cooling operation, without running the engine. The compressor operating speed is not tied to the engine speed, so some noise may be heard from the compressor, especially when air conditioning use is high and the engine has turned off. This is normal. = (Rear Window Defogger): Press to turn the rear window defogger on or off. The rear window defogger turns off automatically after about five minutes. If turned on again, it runs for about five minutes before turning off. The defogger can also be turned off by turning the vehicle off. For vehicles with heated outside rearview mirrors, they turn on when the rear window defogger button is on and help to clear fog or frost from the surface of the mirror. See Heated Mirrors on page 2‑16.