Where is the heating control valve located?
The heater control valve allows the flow of coolant through the heater core to be controlled and switched on and off without affecting the operation of the rest of the cooling system. It may be located on the inlet or the outlet port of the heater core and activated by a cable, electronic control, or a vacuum signal. via
How do you change a gas valve on a furnace? (video)
What happens when you bypass the heater core?
You basically take the two hoses off the heater core, you stick them together and you're done. That way, the coolant will continue to circulate, even though it no longer goes through the heater core. And bypassing the heater core should have no effect at all on the performance of the engine, Charles. via
Why is my car overheating with the heater on?
Coolant can leak out, air gets sucked in, and the engine temperature needle wraps around to full hot. Plugged heater core. The heat exchanger inside your car that keeps you warm on cold days can cause your engine to overheat. If the heater core is plugged, coolant flow restricts. via
Why does cold air come through my vents?
If cold air is coming through the vents when the heat is on, then it could be due to the following: Dirty/clogged air filter. Pilot light is out. Clogged/broken condensate line. via