Driving down the road with the air conditioning on enjoying the cool breeze on a HOT summer day. Then without notice the cool breeze turns into Blast Furnace. Nothing was touched, changed or looked at. It happens all on its own.
The Temporary Bypass
After driving the vehicle like this for years I spent sometime experimenting with the issue. In short I was able to restore the function. What I did was to place the vehicle in neutral and turn the ignition key off and then immediately restart the engine. This causes the Blend Door Actuator to reset itself. And the Cold AC returns to normal for a while. Then maybe a week or a day and it repeats. I do recommend that you pull over and restart the vehicle as a safety precaution.
It gets worse before it gets better
After driving the vehicle this way for years having the cold air switch to hot all by itself it went one step further. During the winter when I needed to turn on the heat, that’s right, now blowing cold air but only on drivers side. Yes i tried to restart it and to no avail.
A NOTE* One thing I think is worth mentioning is an intermittent noise. Its kind of a slight knocking or thumping that sounds like it is coming from the center console area. I found out later that this was also all part of the issue.
The Fix
The fix is to replace the Drivers Side Blend Door Actuator. Watch the video below to see how I replace the blend door actuator on this 2006 Chevy Silverado. Link to Actuator used in video: https://amzn.to/3CMMvfv
Just a few screws and one part and your back in business. Three 7mm screws hold the cover on. A two 5.5mm screws holding the Blend Door Actuator.