[JerTM]

"When the rear heated window switch is pressed and the engine is running, the rear defog control system will remain active for 10 minutes. After the initial cycle has lapsed, pressing the switch again will continue rear window defogger operation, but the cycle will only last 5 minutes. The rear defog control system will function continuously if the vehicle speed is greater than 70 kilometers per hour (45 mph). "

From Service Information. I have noticed on my 13 eco that the defrost does not stay on continuously on my drive to work which is a 65 mph speed limit. I did a quick check through SI and didn't find any service bulletins about the defogger. I will tinker around with mine and see if I can come up with anything.

 

[JerTM]

I just took a look on my digital copy of the owners manual (2013) and it doesn't say anything about the defogger staying on continuously when vehicle speed is above 70km/h. Doesn't stay on anyway.

I do scrape the ice off my windows, but they fog from the inside. I never use the recirculate button, always have it on fresh air. It is annoying to constantly have to press the button every 3mins, as for some reason my car doesn't stay on for the 10mins for first time, 5 mins afterwards. Still too short in my opinion.

Thanks for the feedback everyone.

I got that from General Motors Service Information, it's not likely it's going to be in the manual.