does anyone know where the heater control valve is located in a 1992 GMC Sierra 5.7L/350 half ton?????? my truck has zero heat in the cab when the temperature is set to hot/high. has anyone had this problem??? coolant levels are full everything seems to be circulating, but the heater core takes a while to heat up. i took the heater core out and put the garden hose to it and water came shooting out the opposite opening without any leaks. please help

 

Have you checked to make sure your heater controls/blend door are all functioning as advertised?

 

yes they are all working