Curious to know how many use the Auto recirculation control. I understand that when the left light is on then the "sniffer" senses bad air and engages the recirculation mode. Wondering how useful this feature is as mine does not seem to work and I do not want to spend more on getting it fixed. My left light on the button does not light up and I have replaced the AUC sensor and cleared the fault code. Should I get this fixed or don't bother?