2006 Nissan Pathfinder heater malfunction


#1

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.

Hal


#2

I would check to see if there’s any air trapped in the cooling system.

This can be done by getting the engine up to operating temperature. While the engine is idling, loosen the upper radiator clamp and insert a small flat bladded screwdriver in between the upper radiator hose and the radiator hose neck.

Allow the engine to continue idle until all the air is purge out of the cooling system. Remove the screwdriver and tighten the hose clamp.

Tester


#3

Thanks but since the heat does work I’ve already ruled that out. It just blows cold when the car is not moving and the rear heater controls are on. Having air in the system would cause issues but not the one I’ve described.


#4

In all honesty I expect this to be a nightmare job to effect repair. It will probably involve intensive labor to get at a very cheap part to replace and unless I’m well compensated for it I’ll decline the job because I don’t want to marry it.


#5

I’d rather replace the inboard rear discs on an older Jag than tear apart the interior of a modern car. If you’ve done the brakes on a Jag before then you’ll know it’s not a lot of fun.


#6

I think you’re going to be very limited in what you can do to diag this unless you have access to a scan tool that can give you fault codes, live data, and functional tests to work through the system. Sorry I don’t have any more useful info or direct experience with this model.

I used to work with a guy who liked doing those Jaguar rear brakes. Hour and a half and he’d have the whole rear end assy on the ground on jack stands making it a piece of cake to do the brakes.


#7

This is just a stab in the dark, but if it is zoned climate control, does it use a digital display? There should be a method to putting the climate control in diagnostic mode to pull codes. I found out the method for my Ford, and it made fixing the heat easy by kicking out a blend door actuator code.


#8

Thanks guys, I managed to find a copy of the service manual for the HVAC system and will try running the self diagnostic. If that doesn’t turn up anything then I’ll try to pull info from a scan tool.