drivers side heat is cool while passenger side is hot on 2007 Lincoln MKX

drivers side heating is cool no matter what temp is set while passenger works at whatever temp is set
Coolant level is fine and thermostat is working correctly

Asked by for the 2007 Lincoln MKX
Sounds like a possible temperature blend door actuator - left side - may be failing. A diagnostic test should be done with the Dual Mode Temperature Control (DMTC) system.