This one has me stumped, and I can’t find a rational explanation on the net but it appears to be a known problem. I have a friend with an '06 Nissan Pathfinder that has climate control with dual zones (front and rear) that fails to blow hot (in front) when the vehicle is stationary and the rear heater is on. I used to wrench for a living so I’ve eliminated the obvious. The front blows hot air when the vehicle is in motion and also when stationary and the rear climate controls are off. So clearly it would seem to me that the issue probably lies in the switching of ventilation ducts from hot to cold. I’m not familiar enough with the system to proffer a solution though. The way I see it it’s probably a sensor at best, an issue with the climate control unit itself at worst, or some sort of bizarre mechanical malfunction involving the vents closing when they should be passing air from across the heater core to the entire interior.
I haven’t spent much time diagnosing the issue mainly because I don’t do it for a living anymore. Hot air comes out of the front when the car is warm, stationary, and the rear blower motor is off. My friend who isn’t very technical and speaks English as a second language tells me that when the rear heat is on it blows cold in the front while the vehicle is stationary (in Park or perhaps just when stopped for an extended period i.e. at a traffic light).
Can anyone offer me a valid solution to this issue? I’d really like to help him out without it costing a fortune for diagnostics since the vehicle is well out of warranty. Thanks for your time.