Temperature Valve Control

Recnetly, I posted a question regarding the Temperature Valve Control for my 90 Niss 300ZX (10days), and I haven’t got any response, so I post my problem question again, hoping that someone will give me some answer.

My 1990 Nissan 300ZX has no heat. The temperature control is digital. The blower & fan is working properly. The temperature gauge is normal (center). I checked the Inlet and Outlet water hoses, both are warm. I couldn’t locate the open/close valve for this water inlet. The A/C is working great. I need help to solve this problem. Thank you very much. Hung Vu

Time to find a mechanic that specializes in Japanese imports.
I don’t think anyone here on the forum wants to tackle this without hands on.

I think circuitsmith may be right.

The only thing I can suggest is that if the AC works fine then there is a good chance that the temp control unit is ok.

Somewhere in the system will be a blend door that controls where your air comes from. It may be hung up and not shifting to the right position to allow the heated air in. The blend door would most often be accessed under the dash behind the glove box. But I have no specific knowledge of this car. You could try a repair manual if you are determined to try to sort it out yourself. These will normally give you the run down on components & locations. Or a mechanic.

It may not have a valve ( if both hoses are warm ) but have a plenum door closed.
Don’t know if they’re vacuum or electricaly operated but those doors and motors need checked. ( If vacuum operated, a vacuum leak ANYWHERE in the system would cause doors to default to their zero position, sometimes closed. )