Heating issues 1999 4.3
 

Can not get heat. Blower is working.Flushed heater core and have good flow. There is valve ? Next to the thermostat housing w/ connector. Can anyone tell me what this valve/ solenoid is. Or could it be in the blend door. Thanks

if you have no air in the lines then you may have a thermostat that is stuck open.
does the engine get up to running temp ok? i think that you mean the EGR valve next to the thermostat...unrelated.

next time you dive your truck when the temp gauge is at normal operating temp around 200°f open the hood and the two lines that run into the firewall touch them and feel for warmth your heater core might be clogged and not circulating enough to produce heat. if both lines are hot.then the heater core is not likely to be clogged but.if one line is different temp the the other there is a problem

I guess I should have posted that the thermostat is new. Op temp is good @ 195. Both heater core hoses are cool to the touch @ inlet and outlet also new water pump and with the rad cap off I can see the circulation is good. Thanks

if the heater core lines are cool to the touch then they are plugged. remove them and flush them out. the core may be flushed and the lines plugged..it happens.