Hi all, I posted this same question last year but no answers, maybe now I have better luck...

My father Explorer 1998, is not controling temperature throught temperature ****, after make some reserch I found a water valve that controls coolant flow from engine to heater core.

This valve is vacum actuated and works fine if a manual vacum pump is used, I mean it opens and collant flows to heater and hot air appears at cab grids...

But there is an electric solenoid valve that control vacum for the water valve, this valve also works fine if DC voltage is provided, so it means there should be some sort of electronic controller who take care of electric valve and comand it to open or close vacum for the Water valve...

Unfortunatelly I couldn't fine any controller betwen the temperature control **** and the electric solenoid valve, I gave a look to my Haynes electrical drawings and there is no specific info on that, so my questions are:

1º Somebody knows where is located the electronic temperature control? if it does exist....

2º If no controller is used, then Who controls the electric solenoid valve???

3º A general description of temperature control operation will be appreciated...

Thanks guys... Any comment will be appreciated...

 

No one guys??? come on...

 

Well it seems to me, no answer this year

 

Your problem is tough enough that it requires detailed knowledge of the system. Hopefully, someone else will yet provide a solution.