I just bought a 2004 FX35, which is my first-ever SUV and a GREAT vehicle! One weird thing - when I start the car from cold - I get cool air out of the Vent which continues as long as I drive the car (with fresh air In, Temp. set at 60F). However, if I were to stop and park the car, even for only 10 or 15 minutes, and get back in, the Vent air is now hot - even if the outside air temperature is cool. I've brought this to my dealers attention and they are trying to convince me that this is normal - that it will "cool down eventually". I've owned LOTs of cars and I've never had this problem with the Vent air being hot after the vehicle has warmed up. Any clues? Is this normal on the FX Series?

Does it ever cool down??? From your post it doesnt sound like it.....

Its probably an air mix door, not a common problem.... If your interested i cna look through the FSM and see if theres any self diagnosis you can do!

only after quite a while..... Even if I turn on the A/C, it get cold right away obviously, but if I switch back to the vent only after 5 or 10 minutes, the vent air is still warm.

ok, ive done some research and heres what ive come up with.... The self diagnosis system is exactly like the older nissans....

I had no idea all this stuff was the same, so I will write an article on this.... I will post a link to the article once I get it finished....

In the mean time,you can check this... It shows the position of the various vents...

It appears to me that if you press VENT, it will turn the AC compressor off.... You can verify this by setting it in auto, and then press vent and see if the AC kicks off...

Let me make this article about the HVAC self diagnosis....

Yes, the Ac compressor does turn off. It would be great if you can come up with a solution to this.

I've posted this on other Infiniti sites and others say they have seen this too, that is is a design flaw in the FX Series. They've said that the fresh air intake is in the engine compartment. After the engine is turned off, the air heats up in the duct work and upon restarting the car, the vent air is now warm.

However, if this were the case, I do not understand why the vent air wouldn't also heat up after a long drive.

SOOO, if you can find out anything, it would be GREAT. Today its a beautiful sunny 65 degrees, and after stopping and restarting my car, I've got 80+degree air coming from my vents!!!

Well if the AC compressor turns off, how can you expect cold air to continue to come out??? I know in other vehicles (including my 1994 Q45) that if you leave it on auto and select a vent position (foot, bilevel, vent, etc) that it will remain with the CA compressor on, it will just override that particular segment. IT should only turn off the AC compressor if you go into ECON mode, but I dont think theres an econ mode on those cars.

The intake for fresh air is right by the windshield wipers (thats what those holes are there for)....

So am I correct in saying that all yo uwant to happen is when you press teh VENT mode, you want the AC compressor to remain on, correct? or am I correct in saying you wnat to find a way to recirculate fresh air in that is actually the ambient temperature?

I know what you are saying, but if its cool out, why should I be getting WARM air out of the Vents?

There is no ECON mode on the FXs. Another person suggested leaving on Auto but why run the A/C compressor if its only in the 60s out?

What I am looking for is the A/C compressor off (why run it if its cool out?), cool air out of the Vent when its cool out. So yes, circulate fresh air in that is ambient temperature, AFTER the car has been on/off and then on again. What I dont get is why it is cool when I've just started the car and even driven for a while. BUT if I shut off the car, even for 5 minutes, then start again, then I get warm air out of the vent.

unfortunately, i dont see an "easy" fix for this.... I suppose you could try making sure theres a better seal between the hood and the intake vents by the windshield wipers....

However, im pretty sure the problem is because the heater core always has coolant going through it... on many other cars, the heater core would have a valve to regulate coolant flow through it, but i think on this car, it is not this way... With that being said, the heater core will heat up everything...

Let me ask you this scenario.... Lets say you drive the car for a while, and then turn it off.. When you turn the car back on, immediately switch to the AC, and run it until it gets cold... Turn it bakc to the vent setting, and does the air feel cool, or does it heat up??? If it heats up, i think you probably have a mix door problem... if it stays cool, then you have reached the end of the line.

Scenario: tried that, the A/C does get the air cold as it should. I'd run it for 5 minutes, even 10 or so, thinking that it had to empty the wamer air out of the volume of the duct work. But after shutting the A/C off, going back to Vent/Fresh air, it would still be warm. I've never had any other vehicle do this, so I have to think its a problem and not a design flaw. I can't believe Infiniti would allow for such a flaw (though others haev commented about the same). I'll have to get back to my dealer and ask them about the air mix door....

Do the self diagnosis.... Its really easy!!!!

Within 10 seconds of turning the ignition to ON (engine does not have to be running), press and hold the OFF button.... all of thelights should light up on the climate control display.

At this point press the "warmer" or temp up key, whatever you want to call it. A 2 should initially appear, and then a 0 should appear if all is good.... if its not 20, let me know and ill tell you the code.

After that settles out (gives 20 or some other number(s)), press the warmer key again. It should then display a 3, and then a 0 if all is good... Same idea as before....

Just do those 2 things and report back... your dealer will not perform this simple self diagnosis, and if you can go back to them and tell them exactly wahts wrong, you will have a HELL of a lot more leverage against them!

If that doesnt work out, ill show you how to test the function of each mix door... but do those 2 things first!

20 - ok30 - ok

hey all! i am new to this. i got the same problem with the hot vent air. i did run the diagnostic by pressing the button OFF and hold for 1o secs.
@ 2 it didnt go to zero but it went 25
@ 3 it didnt go to zero but it went 30

can someone pls tell me what is going on