Heater blowing cold air at idle

[amui07]

'06 G35x For some odd reason, even when the car is sufficiently warmed up (ie temp gauge is at optimal operating temperature), with the thermostat set to even 90 degrees, the heater is blowing out lukewarm if not cold air when the engine is idling. The setting is drawing air from outside, but when the car is on the highway or above 40 mph, it blows out extremely hot air. Come to a stoplight for example, and it starts blowing out cold air again. Is something wrong?>

[elwesso]

Yeah something is wrong.... I would take it to the dealer and see what they say, i bet they start with replacing the thermostat.

[JOES75]

I think some 2002-03 altimas had this same problem due to air bubbles in the cooling system. I would have the dealer check it since its still under warranty.

[Skibane]

Usually, if the thermostat is bad, the opposite thing happens: The heater gets cold when you're driving fast (as cold air is forced through the radiator), and warms up when you slow down or stop.

Regardless, if the coolant temperature gauge remains at the same position (i.e., at the normal position for a warmed-up engine) when this is happening, it seems unlikely that the problem is the thermostat.