Cadillac heat problems

This vehicle does not use a Heater Control Valve (Coolant Valve) as coolant is always circulated through the heater core. Rate of coolant flow through the heater core is established by the Coolant Flow Restrictor.

Temperature is controlled with the Air Mix Door which allows or restricts the flow of air through the heater core case.

so if i have no heat its the heater core than?

its on the hoses that go to a/c case. their is a vacume hose going to it.if u manually open the valve when hot heat will come out vents.be carefull use a rag to hold it. its a easy and cheap fix gl