HVAC and dash lights being funky 2009 Tahoe LTZ

[PatDTN]

Many mornings after i leave my dark garage the dash stays in night mode sometimes for nearly an hour.

Lately it's added switching to night mode at random times driving in bright sunshine.

I've disconnected the battery in the past and had the HVAC blow heat from the dash vents. Disconnection the battery again or pulling the fuses usually fixes it. Now if i don't drive it for a couple of days it will go funky. Being cooler outside right now I don't immediately fix it, I just turn the HVAC off. Oddly sometimes that or just turning off the truck to go into a store will fix it.

Do I have a loose or bad ground somewhere that can cause both? The battery is always strong when I start it.

 

[swathdiver]

Many mornings after i leave my dark garage the dash stays in night mode sometimes for nearly an hour.

Lately it's added switching to night mode at random times driving in bright sunshine.

I've disconnected the battery in the past and had the HVAC blow heat from the dash vents. Disconnection the battery again or pulling the fuses usually fixes it. Now if i don't drive it for a couple of days it will go funky. Being cooler outside right now I don't immediately fix it, I just turn the HVAC off. Oddly sometimes that or just turning off the truck to go into a store will fix it.

Do I have a loose or bad ground somewhere that can cause both? The battery is always strong when I start it.

I forget, there is a sensor for this, either on the dash or in the mirror. Did you cover the dash recently or put tint on the windshield or maybe a dash cam?

 

[Doubeleive]

be sure the sun sensor which looks like a little shaded plastic bullet sticking up out of the front center of the front dash by the windshield is not covered, or fell down inside
(it happens)
and like James mentioned above there is another sensor on the forward portion of the rear view mirror drivers side, I think that one just controls the cluster and interior light operation, where as the sun sensor will also control the headlight operation
the sun sensor will affect the hvac operation a little because it sends a signal to the hvac telling it to operate in day or night mode
and the ambient temp sensors outside and inside will also have some bearing on hvac operation

 

[PatDTN]

I don't like tint so no, I haven't added any tint. Nor is there anything over or even near that little sensor on the dash. If it falls in it's the whole thing right? If there's an internal piece that can fall in that bears checking. I was unaware of the mirror sensor so I'll give that a look in case some spider has taken up residence there.

Still I don't think the sensors could explain the operation of my HVAC.

 

[Doubeleive]

I don't like tint so no, I haven't added any tint. Nor is there anything over or even near that little sensor on the dash. If it falls in it's the whole thing right? If there's an internal piece that can fall in that bears checking. I was unaware of the mirror sensor so I'll give that a look in case some spider has taken up residence there.

Still I don't think the sensors could explain the operation of my HVAC.

it's a single piece sensor in the center dash that goes inside and up, so no there is not some internal part that could fall in and leave just a empty bubble.
a temperature sensor can very well affect the hvac, namely there is one above the drivers head in the headliner that looks like a little tiny speaker, if you have the bose system there will 2 of them side by side and there is another in the rear passenger side that controls the rear heat.
if the drivers headliner sensor is not giving a accurate reading it can make the hvac heat or cool incorrectly, it consist's of a thermistor and a little fan. the ambient air passing over the thermistor changes the ohm's reading and the hvac reacts accordingly. if you determine that is part of the problem it is easy to replace and only cost's about $25 online.

 

[PatDTN]

The HVAC behavior when it goes funky is exactly like when it needs to be reset by cycling power to the entire system. I'm concerned something is making the power intermittent.