Cadillac Repair: not much heat, heater hoses, colder the air

Question
Hello,

I have a 91 sedan deville. The air that comes out when it is on heat is not very warm.  If is is not very cold outside, it does pretty good, as the outside temp gets colder, the air coming out of the heater is pretty cool.  The heater worked great when I got the car a few years ago, this condition happened last year.  I have the factory service manual so I was able to enter the codes to go into diagnostic mode.  It tells me my water temp when the car is warmed up is around 215f.  The damper door sensor tells me it is in the 100 % heater position.  Is there a valve that could be restricting water flow to the heater core?

Any suggestions appreciated

Answer
check your heater hoses at normal operating temp. One should be extremly hot and the other slightly cooler.

The engine temp of 215 is OK. The damper door is saying it is at 100% but did you physically look at the damper door actuator rod located behind the glove box by removing the glove box liner and looking at the rod as you command it to move ?.

Possible faults:

damper door actuator rod not moving.
plugged heater core.