Hey all, 149K on a 2011 QX56. When the Air Conditioning is running I often get medium air from the driver's side, cold from the passenger side, and hot air from the rear. When driving, all areas seem to cool down a good amount. Revving/RPMs at a stop doesn't seem to have any effect on temps. My service manager suggested assuring the coolant was up and that the condenser is clear of debris, both are. As I understand it, there is no condenser fan, so if correct, that's out of the equation. I've seen a few posts about the sun load sensor? Would trying manual cold and fan full-blast take that out of the equation? If so, I did that and no luck. Thanks all, this forum rocks.

Sounds like a mechanical problem in the air ducts. It either blows cold or it doesn't. You can't have both going on at the same time unless the air circulation and directional duct vents are not operating correctly. Turning on the A/C should move a vent door to block air from passing through the heater core and move the circulation to pass through the evaporator core instead. It sounds like the vents may not be opening and/or closing the way they should.

Thanks for the input. For what it’s worth, I had a similar issue a year or so back, someone suggested that when it’s low on AC coolant (R135 or whatnot) you can get strange cooling issues like this. I had it recharged and the problem seemed to go away last time so maybe I have a pinhole leak somewhere?

Hey all, quick follow-up. After topping off engine coolant, researching the sun load sensor, the blend door, etc I decided to buy a refill kit from my local auto parts store. When hooking up, it was mid-"green", if memory serves it was 30 PSI. I decided to pump it up but keep it well within the green zone of the recharge bottle. I took it up to within 5psi of the top of the green band and viola, the entire vehicle system works like a charm, at idle and at all speeds including parked. Just wanted to follow-up for anyone else experiencing the same thing. It just needed a bit of refrigerant.