Hey guys, just noticed this problem today and wanted to see if there was a quick fix without a ton of research first on my part. It seems my heat is intermittent - if I turn off the car (and I think just turn off the blower motor), then turn on heat, it might end up just blowing cold air even though it was warm just a few seconds prior. I don’t have much experience here but feel like this must be a valve or solenoid issue. I don’t believe it’s a stuck thermostat or blocked core or air in the system, it wouldn’t get warm at all then. I looked under the hood but couldn’t locate any valves in the heater core hoses. Any ideas?

PS I drive a 2002 Infiniti i35 with the same VQ35DE engine as the Maxima

This, coolant is not something that just disappears. Its leaking somewhere, hopefully its just a bad hose and not a head gasket. Check your oil and pray it doesnt look like chocolate milk, although if that were the case you would probably know by now.