NO HEAT!!! PLEASE HELP!!!

[MikeDumelow]

First off, vehicle is 2010 QX56. Noticed on a trip to New Orleans a couple of weeks ago that the dual climate controls had quit working (Driver side @ 60 - temp same on the frozen wife's side). Then just recently, after a cool morning and in need of some defrost action, truck only blows COLD AIR. No heat from driver, passenger, or 3rd unit.

Anyone experienced the same problem, and if so, what / how much was the fix???

Thanks in advance!!!

[marctronixx]

heater diverter valve could be stuck. its in the engine room. has two hoses (going from memory)pipes that run into the cowl area into the hvac unit in the dash.

[MikeDumelow]

Called Infiniti.... $120 part. Is the Nissan part the same on this truck? I have tried to research this on my own and am coming up blank. Since they are basically the same truck, was hoping the Nissan part would be cheaper. Any advice on this??

[marctronixx]

same truck on the same line.

call up a nissan parts depot and tell them the name of the part.

[MikeDumelow]

UPDATE: Bought a "heater diverter valve" from Nissan (same price as Infiniti, go figure) and had it installed..... STILL NO HEAT!!! I put a test light on the electric clip that plugs in. If my memory serves correct, this valve is little more than a solenoid. In a two-wire configuration, one side should be hot and the other cold. When activated, they switch polarity to either open or close the valve. Problem is NEITHER side is hot (power) regardless of temp setting.

With this thread at almost 200 views, I feel not so alone in the matter so any help for myself and other viewers is GREATLY appreciated!!

[marctronixx]

right so if you are not getting power to the part, you need the schematics to trace back to the fuse panel to see if there is trouble at the fuse box. its a simple part so not much to troubleshoot.

[MikeDumelow]

Looked at a schematic... Looks like the circuit that feeds power to that diverter valve is a direct feed from the climate control head unit. Will look in fuse box to see if any problem exists there anyway, but from what im seeing it might be the head unit itself. Replacement part from Infiniti of Mobile is $235.

If climate control head unit is replaced, does the truck have to be reprogrammed?

[marctronixx]

the instrument cluster and head unit are the main parts to the entire CAN bus system. being that this system is serial in nature, all of the commands run through both parts.

you should be able to swap out the HU as long as it has the exact trim options your car has form the factory. if you dont swap with the same type of head unit with the same trim options, you will get error codes as the BCM will be looking for certain sensors that may or may not be on the car but are built into the firmware version...

[mdstahl1]

I know you may be chasing an electrical issue, but I'd thought I'd share what I did to solve my heat problem.

http://www.titantalk.com/forums/titan-p ... umber.html

This link gave me a clue to open up the heater valve on rear bulkhead (passenger side). 3 screws out and turning the knob clockwise (you can see it's notched to go one-way), got my heat working again. It's been a few months and I haven't had any adverse conditions.