2008 Heat Issues

I have an 08 Sebring convertible 2.7L supply hose (bottom) at the firewall gets hot but the return is just warm,which to me indicates a restricted flow
So my question is does anyone know if this system has any kind of a flow control or valve that could be malfunctioning?
If not the core will have constant flow and heat which is a problem in summer .
So does anyone have any suggestions on getting flow through the core again?
Thanks in advance everyone ,Carl