none,,it will go either way.
Heater core plugged? Heater core airbound? Thermostat not opening to allow coolant flow?
On my 1995 Ford Explorer with 4.0 L OHV engine , where the heater hoses are connected right at the firewall , the hose nearest the driver's side is the supply hose to the heater core , and the hose nearest the pasenger side is the outlet from the heater core. (Helpfull)
The presence of the valves usually restrict the coolant flow into the heater core.
Doesn't matter which way the water flows. The heater core is just a tube with fins and water can flow either direction.
Disconnect both hoses that go to the heater core from either end, (the end at the heater core or the end at the water pump, manifold, radiator, etc.) using a garden hose, preferably with a hose repair end attached to plug into the hose or a short piece of hose cut off to connect to the heater core, run water in each direction through the heater core until water runs clear, then reverse direction of flow. Repeat as many times as necessary until flow is restored and water runs clean. Be sure to also flush the rest of the cooling system or debris from it will likely just clog up the heater core again.
Disconnect both hoses that go to the heater core from either end, (the end at the heater core or the end at the water pump, manifold, radiator, etc.) using a garden hose, preferably with a hose repair end attached to plug into the hose or a short piece of hose cut off to connect to the heater core, run water in each direction through the heater core until water runs clear, then reverse direction of flow. Repeat as many times as necessary until flow is restored and water runs clean. Be sure to also flush the rest of the cooling system or debris from it will likely just clog up the heater core again.
It does not have a water flow valve in the heater plumbing.It does not have a water flow valve in the heater plumbing.
The heated coolant comes out of the engine from the connection in the intake manifold and returns thru the connection into the water pump.
Heater core may be air bound and have to be bled Heater core may be plugged or restricted Thermostat may not be opening allowing coolant flow to core
The best bet is that the valve that controls the flow of water to the heater core is not functioning, but on some cars it's the flaps that control the air flow through the core.
Antifreeze is used to heat the cab of your vehicle. When you turn on your heat in your cab, it opens up a valve that allows the hot antifreeze to flow from the radiator into the heater core. If there is a leak in the rubber tubes that flow into the heater core, or if the heatercore is damaged, you will smell the antifreeze in the cab of the vehicle. You may need new hoses to the heater core and/or a new heater core.
they run from two points by the fan in the front by the water pump to the heater core routed along the passenger side wheelwell until they reach the heater core either hose can go on either location because a heater core exchanges heat the same no matter which direction the flow passes in it. I hooked up mine so that the hoses stayed parallel to each.