The heat on my driver’s side sometimes stops working - blend door actuator?

Roy it worked! I cannot thank you enough. I cannot wait until I have another question.

Yes it's dual climate control. I was driving one day and the air went from cold to hot. I took the actuator off right below the glove box. Kind of easy to get too. I took it apart just a little bit not all the way. I see a whole lot of greasy build up inside of it. Didn't want to take it apart just in case it was the wrong one. Checked all fuses. None are blown. Turned on my rear a.C. In my truck and it blows heat as well. Also how will I know if it's the a.C. Compressor itself? The heat and defrost works fine.

Roy, I was driving today and noticed the heat is only working on ninety degrees again on both sides. Perhaps my check was not good enough. I pulled the fuses again and verified the system reset and still have the same result. When I go from ninety to eighty five for example I watch the actuator click and keep moving until it is wide open more or less. I am wondering if it could be anything besides the control unit itself which I can get on eBay for $160.00. Before I broke out the parts shotgun I wanted to see if you thought it could be anything else besides the control head unit or the actuator itself. Thanks again.

When you say outside are you referring to the temperature sensor that senses the outside temp and displays it on my climate control panel? If so, yes it displays the correct temp outside. Regarding the inside temp sensor, I am familiar with the sensor by the driver head, but I was unsure how to check the sensor.

Thanks. I was told this can be caused: by a fault with an internal air temp sensor. If you have an air temp sensor that is sensing the interior is hotter than it actually is when you set the heat, anything but 90° it will keep cool like this. When set on 90° this bypasses the temp sensors and it blows full hot no matter what the temperature is inside the vehicle. I have seen this type of fault before and it is usually a temp sensor failure causing this needing replaced. Question is, how do you test the sensor to confirm if it is bad?

I read this and it sounds like a match, im going to look at it

After further investigation it looks like it is going to be the sensor. Thank you for telling me about that. I am going to work on getting it out of there.

I took it out and ordered a new one, I had voltage at the plug so hopefully this works. I definitely learned something.

Roy, I replaced the sensor and it fixed it. Would have never known to look there without your input, thanks again I really appreciate it big time!

Roy, can you please tell me what the tool is for that comes with this ac compressor belt? https://www.carid.com/acdelco/gm-original-equipment-air-conditioning-compressor-belt.html?relationshipId=1283192578&childId=544539638&gclid=EAIaIQobChMIg6aA_Z-i2gIVy7rACh2KyQXfEAQYAiABEgLeofD_BwE#specifications