I have a 2008 G35x sedan and I have a problem where my heater will blow hot air when I turn the heat on and then blow cold air after a while (maybe 10 minutes or so). The issue happens even when I am moving and not only when idle (like many posts I've seen when researching the issue). When I increase the heat, it heats back up at the higher temperature (usually up in the 80s). I was wondering what the problem might be. FYI the AC works just fine during the summer and this problem seems to just affect the heat.

 

okay I'll give it a shot

 

I performed the first test and everything checked out. I did the second thing and the indicators lit up and nothing has happened since. What's the next step after that?

 

darn..i bought my '08 G35X only last week. I got the same issue. Was driving on highway with outside temperature around 45F.. and the heater started blowing cold air! I increased the temp and then for a while, it was fine. But again, cold air after sometime.

Did you find any solution? Going nuts with my purchase..

 

Go to the dealer and let them check your AC motor. This happened to me and it end up my AC motor died on me.. NO hot air just cold air.

 

I'm new to the forum but am having a similar problem except for worse, much worse, because I live in Utah and the temps are barely above 0. I have a 20 minute drive to work and the stupid heater doesn't blow any air out <at all> until I pull into the parking lot at work. When I drive home from work and the temperature has risen to a balmy 19 degrees F, the heater only takes a few minutes to start blowing. What should I do?

 

Got the same thing but recently an issue started where the heat just blows ***** hot no matter where you adjust the temp. I don't have time to muck with it right now, but I will have it looked at during the next oil change.

 

Wanted to revive this thread. Going to the dealer to have this issue looked at. Will post up any findings.

 

Sounds like the blower motor relay. It is located on the back of the fuse panel behind driver kick panel. When it does this, pop the access door off and smack the fuse panel and see if the blower starts working. This is pretty common on 05-06 models

 

Thanks for the info. I guess I'll see what my dealer tech says. However, that issue has sort of taken a back seat to my current heat issue. Currently my heater only blows ***** hot until I set it to 60. If I set it to 61 to 90....Hot. Nothing in between.

 

Update. Heat issue is fixed.

My internal ambient temp sensor was gummed up with dust and who knows what else. They cleaned it and the heat is working like it should. This was due to the heat running hot at any setting. I would have this checked for the heat cutting out as well along with what Jason recommended.

 

I have had this problem with 3 Infiniti's and a Maxima. When driving highway speed in cold weather after awhile, it starts to blow cold air. Raising the temp helps - but my wife is always complaining about how cold it is and raises the temp on her side to 80 degrees and still cold. Not sure what it is - but seems to be prevalent on Infinit/Nissan