I am having the same problem. I ran the self-diagnosis and got codes 50 and 52, which are “Optical sensor circuit open or short” for driver and passenger. After looking at the manual http://www.nicoclub.com/FSM/quest/2005_Quest/atc.pdf Page 136, I’m not sure this is the solution. I haven’t tried it yet, though.
Just wondering if you got yours fixed. It’s 100 degrees here in Mississippi, and I’m not sure I can take this any longer.