Had another block put installed, can't get the heat to operate, the hoses going into and coming out of the engine block is hot, I physically checked to see if fluid is flowing, that's good. The Heater switch on the back is open. There's no heat coming out any suggestions.

 

clogged core?
do a flush

 

..... heater core maybe done???

 

If the heator core was clogged, why would BOTH in/out lines be hot??

Maybe the cable controlling the cold----hot is not moving.

 

Because the fins can be clogged (internally) while still being able to flow through the end.