Heater Valve/Core Operation

[7Dcuda]

On a 70 Cuda without A/C, can someone explain the heater operation.  There is no heater control valve in line with the heater core hoses from the water pump to the heater core firewall connection.  I've read that for cars WITH A/C there is a control valve or "water valve" on the heater hose from the water pump to the heater core.  So my question is this:  Is there a heater control valve on non A/C cars and if so, where is it?  And if there isn't a heater control valve what controls the flow of coolant to the heater core and where is it located and how does it work.  Thanks in advance for any info.   

[Chryco Psycho]

there is no valve in the hoses , just a door in the heater box that either allows air through the heater core or closes it off , water constantly flows through the core

[7Dcuda]

Thanks...so where is this door in the heater box?  Is it on the drivers side or passenger side of the box?  Is it one door alone that allows air in to all vents?

[Chryco Psycho]

there are 3 doors , 1 for the vent air , 1 for heat defrost & one to direct air flow through the heater core , the heat door should be center top area , move the heater control & watch which door it operates , the defrost door is near the gas pedal & the vent is the other end of the box