you should be prepared for the daunting task of taking out your HVAC assembly.
this is by no means an easy task.
be prepared to spend at least a week or two of study on how to perform this procedure. in fact, it will pay off greatly to tear one apart at the junkyard first. this will help get you over the extensive learning curve to safely break into your own dash and remove the assembly.
you will probably need to remove the seats. you will probably end up removing the radio and center console. if you have a center gear shifter or selector it will probably need to come out. the instrument panel cluster may also have to be removed. the steering wheel may or may not have to be removed (which may involve air bag removal) all the bolts holding your dash will be removed. the hard-line heater core lines will probably need to be disconnected. Also… the a/c system will probably need to be evacuated and the lines going to your evaporator will probably need to be disconnected. there will also be an array of vacuum lines that will need to be disconnected from the hvac assembly. the blower motor electrical connections will need to be disconnected.
IF.. you make it to this point, and you have the hvac assembly out of your vehicle, you can begin testing the various actuators by using a hand-held vacuum pump. if you apply vacuum to an actuator and nothing happens, then you have found the problem. you can get a new actuator at autozone for relatively cheap.. or since you have already done some ‘junkyard practice’ you will have access to cheap actuators.
Re-installation will involve the additional steps of placing the a/c system under vacuum then recharging the system.
Breaking into the HVAC assembly is the most difficult a/c work one can do. This is one of those things where the parts are cheap, but the time and labor is tremendous. I would give this job a 9 out of 10 on a scale of difficulty based soley on the steep learning curve and the need to legally evacuate the a/c system. the nuts and bolts aspect is straight forward but there is difficulty in actually locating all the dash fasteners you need to remove.
watch a lot of youtube on hvac assembly removal
do a lot of study on hvac assembly actuator failure
if you feel this task is too great, it is better to make the decision early to take it to a professional.
if you do not have 2 or 3 days off to work on this project, then take it to a professional.
if you do not have a great deal of patience, take it to a professional.