My 2008 Frontier won't heat/defrost cab when idling.
When idling cab won't heat/defrost won't work. Engine temp. rises as expected. Cab/defrost begins working when you start driving.
Could be a bad thermostat, dirty cabin filter, bad/plugged heater core or the electric cooling fan by the radiator isn't working.
sometimes the little doors that direct heat around are run by engine vacuum. check for vac leaks.
On something that new I'm gonna guess and say the blend door(s)are electronically controlled by small motors.
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