I live in AZ where inside the car can get 120+ I always try and cool it down before putting LO in but I don't feel like she is getting air because she is rear facing.
One of my friends recommended the product from the site below. I just ordered one and can't wait to try it...
The previous winter post got me thinking this is beneficial for heaters in the winter too! So I wanted to share with everyone

www.nogglenation.com
Re: AC/Heat for rear facing car seats
Lately I have been wrapping it icepack in the towel and putting it behind little ones head or on her lap. It has helped but obviously is not ideal.
Ginny DX 21-Hydroxylase Deficiency Congenital Adrenal Hyperplasia
Charlie DX Specific Antibody Deficiency & ASD
BFP #2: 11-7-14, CP (BFN: 11-13-14)
BFP #3: 3/24/15 EDD: 12/5/15