If the knob is broken go to the dealer and buy a new one they are like 10 bucks a piece. They install by just pushing them on.
There may have been some water left in the heater core when you disconnected both hoses at the firewall. I can't think of any other explanation since there is no water circulating through the heater core.
No, the inside temp is controlled by a temp door inside the heater box.
Loosen the dash and pull out the complete heater box after you have disconnected the heater hose from the firewall...........
If your heater control is manual you probably have a cable that has become disconnected at the heater control valve or on the back of the panel. If you have an automatic temp control system you probably need a new temp control panel.
The circuit is open. Wires could be disconnected/damaged or the heater element is burned out.
yes if it stuck open.
Blocked heater core, faulty heater valve, disconnected connection to the heater valve.
its most likely the heater core that's leaking
It is in the middle of the dash, inside the hvac housing.
Switch problem? Cables disconnected?
Doesn't have any. The system should self bleed.
Not if it was disconnected properly