I have a 2012 Infiniti G37x, and I've noticed something odd while using the heat in my car. While the vehicle is running at operating temperatures and the heat is set at 32 degrees Celsius (89.6 Fahrenheit) with the fans at max what I'm noticing is when I am stopped and idling at a red light or something, the air coming out of the vents begin to cool. So I did the first thing, and Google'd around, and the first thing that popped up is that there is air in the cooling system. So I go and buy some 50/50 pre-mixed fluid and begin burping my system. I thought I solved the problem and this morning, the air coming out of the vents is still coming out cold.

Am I missing something? Bad thermostat or water pump? Did I not burp all the air out of the system? I might try burping the system again and leave my car on ramps for the night to see if that helps.

Anyways. I'd love to know if anyone else has had similar experiences.

 

Was your car able to maintain desired temperature in previous winters?

 

Does warm air come out if the fan speed is slowest or slower?

What's the outside temp?

Maybe a thermostat that's partially sticking open?

 

I don't think I've had an issue previous years. If it was dropping in temperatures, probably not a significant amount.

Outside temperature when I first noticed the problem was about -21c (-5.8F) so the air would cool down really fast. Today was only -13 and it was still happening.

Warm air does come out if the fan speed is the slowest to middle speed. When it's max, I noticed how quickly it drops.

The outside air shouldn't cool the heater core that fast?


EDIT: I'm going to try to burp the system again and if that doesn't resolve the issue, I'll replace the thermostat when it's warmer outside, if that's not it, maybe my heater core needs to get flushed. I'm hoping it's not my water pump because that would suck

 

I'd say it's pretty cold where you're at. If the system is set to pull in refresh air (not recirculate), then the system has to warm up that really cold air. Heater core is nothing more than a mini radiator. Warm air is achieved by blowing air through the hot fins. If it's blowing too fast and outside air temp is very cold, it may not be warming the air up fast enough.

I don't recall what mine does as I rarely have the fan on max speed. It's on a slower setting while the car warms up, then low to med as I don't like baking in the car.

I really don't think you have an issue. Wait for some more responses from folks who duplicated your test conditions and have similar outside air temp.

Set it to recirculate then repeat your test.

 

It does get pretty cold here. I didn't think the outside temperature would cool my heater core at the rate it did. When I got home from work today, I set my system to recirc and noticed that the decrease in temperature from my probe was not as fast. It does prove what you're saying because the cabin air is already warm. If anything it increases the heat coming out of the vents slightly.

I'll keep an eye on it, but at the rate in which the temperature was decreasing while idle or stopped just makes me wonder if my cooling system is operating efficiently.

I opened up my rad cap prior to driving and it was pretty full, so there shouldn't be a loss in fluid.