Radiator Flush now no heater is spotty
 

Had the radiator flushed and new tstat by the stealership. Car is 6 years 4 months old with 65K miles.
Did not have any problems with overheating or heater functions or anything. Just preventative. Car takes a long time to reach operating temp and the heater works only when you are driving. When you stop, cold air comes out. WTF
Please help.
Thanks.

So after the dealership you experience these issues?

Air in the system is the first thing id check, of course if my above statement is correct then the dealership should warranty there own work and check on this issue if you present it to them

Yes sir after the repair/service.
Is it safe to drive? NO chance of overheating or just keep an eye on it?
Thanks for the help.

They may have either used wrong temperature thermostat,put it in upside down or either left it out.
Air in system usually causes an overheat symptom-but unsure on these engines.
Make sure coolant is full in reservoir & demand one of their certified technicians re-work the job...yes it’s safe to drive.
Take back ASAP; as this condition is most likely going to throw a CEL as well.

Sounds like a faulty thermostat ...stuck open ...I would take back and have them correct the issue.

Yep,,,that as well.
Here in good ol’ SC... I know of a few dealerships who don’t always use oem parts.
Just something to think about.

+1 Sounds like your thermostat is not opening. I would ask this Nissan dealership service department what brand parts they are using on your car? I would only use Nissan OEM parts on your 370Z.

Looks like you have a few answers, regardless.. Take it back and ask for them to check it over

To me, it sounds like air in the system. Even if the thermostat is stuck open, the coolant should still be warm-ish. If there is heat when driving and none when you stop, there is not enough coolant to reach the heater core.

My $.02...but either way, take it back and get them to fix it...Let us know what they find.

Most of the time air in the system will run hot ....

The engine will usually run hot but flow to the heater core can be blocked by air pockets, especially when the water pump is at low speed. The coolant in the core cools off quickly when flow is lost.

If the thermostat will not open. The car overheats. He doesn't have that problem. Most likely there is air in the system that needs burped out. The thermostat can not be installed backwards. It's apart of the housing.

Push back from stealership
 

Thanks gents for the responses. The vehicle is not overheating thank god. However, I do believe after looking through many post that there might be air in the system.
I didn't know there was such a thing from just replacing coolant!
I spoke with the service manager today. I got a little push back from him. The turd.
It is my wife's vehicle. I don't want to stereotype but she didn't really notice the issue because she has not had to use the heater. Just recently the temps dropped and she has turned on her heater. It has been 6 weeks since the service. I drove the car this weekend and she is correct the air temps is significantly cooler when the vehicle is at idle. I was like WTF?
Anyway, I might take it somewhere else. The service manager was a complete douche. And I'd rather not have his people jack up something else on the car. It has been amazing and incredibly reliable for my wife who has always dreamed of owning a Z. I will keep you posted. Thanks again.

I had a similar experience in my S2000 before. What I noticed would happen though is when I turned the heater on, it would blow cold air for about 5-10 minutes, then finally get warm but also cause the engine temp to skyrocket at the same time.

The issue was resolved by burping the radiator to release air bubbles and adding more coolant as necessary during the process (turns out I didn't put enough in while flushing it in summer). Even at the dealership it's humans who can make mistakes. Hope that helps.

Yea you have air in the system, should be very easy to bleed, might need to add more coolant. The nissan systems can be a pain sometime, I know it was on my g35