You didn't mention what year Blazer you have but in most cases the blend door actuator is located on top of the HVAC box that is located behind the dash assembly. Unfortunately, the entire dash assembly must be removed to gain access to it.
Where is the blend door actuator located on a 2005 malibu
Remove the dash assembly to gain access to the blend door actuator.
If you are refering to the temp blend door actuator, it is located behind the dash on top of the HVAC box. The dash assembly must be removed to gain access.
The temp blend door actuator is probably at fault.
The heater blend door is not run by vacuum. It is run by an electric actuator.
Probably won't be fixable, it is electronic. Replacement is necessary. Dash assembly must be removed to gain access to the temp blend actuator.
where is the blend door machanism (acuator) located in my 1998 toyota camryalso how to fix
I believe it is located behind the glove compartment. Drop out the glove compartment box and you will see the blend door actuator.
The temperature valve actuator is located on the front of the heater case
The blend door actuator can go bad. Big job to replace it. Dash assembly must be removed to gain access to it.
under the glove box
You will need to remove the dash assembly to gain access to the blend door actuator. Recomend purchasing a shop manual of you intend on doing that job.