Here's one for you:
Bought new (2017) Pathfinder on May 27th which was Saturday of Memorial Day weekend. Took delivery with 16 miles on it.
Over the weekend I discovered it had no heat, even with the climate control set at max (90 degrees). Just blew cold air.
Took it back to dealership on day after Memorial Day. May 30th.
They confirmed it had no heat and gave me a loaner.
I also mentioned to them that after the first two times driving it I smelled an electrical burning odor coming from the engine compartment. Didn't smell it in the car. After driving it for a while the odor went away and I didn't notice it again.
I checked with them a couple of days later and they thought it had an air bound heater core. They were trying to purge the air out of it. Tried several times, following Nissan procedure. Still no heat.
They brought in a regional Nissan "super tech". Neither he or the dealership techs could find the problem. They got Nissan Engineering involved. Nissan Engineering decided that the engine may have a bad block casting or a plastic plug that was supposed to be removed before assembly was overlooked. They ordered a new engine to be shipped to the dealership for installation.
Meanwhile, I had done some research and had reviewed the engine cooling system and heating core diagrams. Couldn't find them for the 2017 model but found some for some of the previous years. There is a component called a "Heat Control Valve" mounted somewhere in the engine compartment. It's purpose is to control the amount of hot coolant flow from the engine block to the heater core. If you set the climate control to "90", it should open completely, allowing max flow to the core. If you lower the temp or are using A/C it should shut, blocking flow to the heater core. It's apparently actuated with a small DC motor that turns some gears which turns the valve either open or closed or somewhere in between.
I mentioned this to the service manager. Told him it was just a hunch but if that valve was stuck closed (maybe one of the little gears was jammed), the little motor would be locked, drawing current but not able to move. The windings of the motor would get hot, explaining the electrical burning odor. Eventually, the winding would open, current would stop and the odor would go away. But the valve wouldn't open because the motor was burned out. They thought this was a good theory but they are required to do what Nissan authorizes them to do under warranty repairs.
Anyway, it's now been almost a month. I only had the Pathfinder for 2 days. It's been at the dealership since. Today I found out that the new engine has been installed and tested. Guess what? Still no heat.
I have a case number with the Nissan Arbitration people. The representative has been friendly and helpful. She told me that if the new engine didn't fix the problem that Nissan will not "drag this out" and they will buy back the car and refund me.
Anyway, I still think my theory is the problem. They can only fix what shows up on a diagnostic computer plugged into the ECU as a fault code. There were no codes for this, but as a retired electrical/electronics engineer I can understand why. The diagnostics probably just looks to see if 12 volts is being applied to the heat control motor, which it would be. It just would not have any current if the windings were burnt out. So, no fault. The fact that the motor isn't turning probably isn't covered by a code.
So, we will see what Nissan decides to do on Monday. I don't think the representative knows yet that the new engine didn't fix the problem. Other than no heat, I like the Pathfinder. I've just sorta forgotten what it looks like.