Yes, it is possible the blend door is broken in the heat position.
How do I locate the heater blend door actuator in a Ford f150 pickup
If it is broken. It could be a faulty temperature blend door actuator.
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The temperature valve actuator is located on the front of the heater case
The heater blend door is not run by vacuum. It is run by an electric actuator.
Could be, low on coolant, bad thermostat, plugged heater core, faulty temp blend door actuator,
Could be, Stuck open thermostat, Low on coolant, Plugged heater core, Temperature blend door actuator malfunction.
Could be, low on coolant, stuck open thermostat, plugged heater core, faulty temp blend door actuator,
You have a faulty temperature blend door actuator located directly behind the radio. Remove the radio and remove the blend door actuator held to the heater case with three 8mm screws, and replace it.
Could be low on coolant or the thermostat is stuck open or the heater core is plugged or the temperature blend door actuator is broken.
Could be, Low on coolant, A stuck open thermostat, A plugged heater core, A faulty temp blend door actuator,
I believe you are looking for blend door actuator???