HVAC Question

[Bacnbit]

Ok guys I have an HVAC pet peeve. Search function no help. unless i missed something. Just redirect if I did.
The heat/ac will decide on it's own if I am to hot or to cold and turn it self on to max settings either way hot or cold. It will happen any random time highway,lowspeed, hot, cold, wet dry. it does not coinside with out side temp. it could be 80 and the heat will come on it can be 50 and the ac will come on. Temp readin is accurate not stuck at 50 like when the temp sensor shorts.

I have pulled the interior temp sensor out of the sail/b pillar, it is clean and connection good, no loose pins and did the same for the the exterior temp sensor.
Not having access to a TechII and Alldata any longer. part of me thinks there is an update/reflash for this. Does anyone know if there is or can run a search for me. Because if I had the info I could call around to some locals and see about having it done. I may just throw a 8$ exterior temp sensor in and see what it does. Because i will be damned if I let anyone else touch my truck especially the general. I left the Auto repair industry after 25 years and it sucks to have to have someone other than myself work on It.

[Trail X]

Does it only ever go to the max hot or max cold, or does it go to either one?

I agree that it sounds like a bad connection or ground somewhere. I would have suspected the internal temp sensor over the external. Also, is the little fan in your B pillar working correctly?

[Bacnbit]

Does it only ever go to the max hot or max cold, or does it go to either one?

I agree that it sounds like a bad connection or ground somewhere. I would have suspected the internal temp sensor over the external. Also, is the little fan in your B pillar working correctly?

Trail that is what it does it goes max hot and or cold. Yes the the fan function correctly. The only reasoning behind exterior temp sensor replacement is due to the higher failure rate. The internal temp sensor isnt that much either. And is still quite. Its not a problem that plagues me just stupid litte S**t bugs me.

[Trail X]

So it ONLY goes max hot or max cold? Or it sporadically goes into one of those modes?

[The Roadie]

When it's working properly, it obeys all your commands? And the only command it ignores when flaking out is temp? Both sides the same or do the split controls do anything differently? The plenum sensors if they're working, shouldn't allow a bad b-pillar sensor to rule the controls. I'd put a meter on the reference voltages coming out of the control module to the sensors and actuators.

[Bacnbit]

So it ONLY goes max hot or max cold? Or it sporadically goes into one of those modes?

Max Hot Or max cold Only.

[Bacnbit]

When it's working properly, it obeys all your commands? And the only command it ignores when flaking out is temp? Both sides the same or do the split controls do anything differently? The plenum sensors if they're working, shouldn't allow a bad b-pillar sensor to rule the controls. I'd put a meter on the reference voltages coming out of the control module to the sensors and actuators.

When functioning it Obeys to the T.
Yes temp is the only thing affected, so of course fan speed max's out to compensate temp.
Both sides react together exactly no split change.
Roadie- I would love to put a meter on the reference line but it is so intermitent if you were to check this voltage any other time it would be right on the money. I probably could put my mutimeter in line and just let it ride along and when it flakes look at it then.BUt then I would have to do one reference line at a time. PITA. OHHH i miss having access to a TECHII