Defrost on Dash but no Defrost?

[Matthew Jeschke]

My friend has a 2005 Z71 extended cab Silverado. It is a great truck, he has never had issues, just this one lingering question he challenged me with. His truck has no rear defrost on the rear window. However, the controls for the HVAC include a button, which would normally be for the rear defrost no? But what does it control? If anything?

 

[Tonyrodz]

My friend has a 2005 Z71 extended cab Silverado. It is a great truck, he has never had issues, just this one lingering question he challenged me with. His truck has no rear defrost on the rear window. However, the controls for the HVAC include a button, which would normally be for the rear defrost no? But what does it control? If anything?

View attachment 342954

Someone probably replaced the headunit from a junkyard.

 

[Matthew Jeschke]

I think he owned since new. I'll ask him if he ever replaced that.

 

[Doubeleive]

or if the rear glass was replaced with one without the defrost wires

 

[Doubeleive]

could be for heated mirrors also