Dash lights going out and on and temperature controls not always working

Tiny
BBORTNER21@GMAIL.COM
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 6.6L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 300,000 MILES
My dash lights will dim and or go out all together, then come back on. All the gauges always work and it does not effect my driving lights (outside of vehicle). Sometimes playing with the dash light brightness control will bring them back on. This also effects the radio lights too, yet the radio still works. My biggest issue is the temperature control, many times it will be dark and you can not control it at all. When it does come back on many times it will be at 60 degrees like it has reset or something. My air also is impacted and doesn't always work (blowing warm air), yet other times it works just fine. This morning on the way to work the dash lights were flickering and then all came on and worked fine. Any thoughts?
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Thursday, October 3rd, 2019 AT 6:40 AM

7 Replies

Tiny
94 TRANSAM
  • EXPERT
Hi and welcome to 2CarPros.

Out of the gate it sounds like you are dealing with 2 different issues.

Your illumination circuit is controlled by the dimmer. If they work at all which you indicate they do then you likely need a new headlight switch to fix that issue. You can find them very reasonable on Ebay or Amazon.

The climate control is much more complicated given its an intermittent issue. Let me research this and get back to you ASAP.

Rich
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Thursday, October 3rd, 2019 AT 10:08 PM
Tiny
BBORTNER21@GMAIL.COM
  • MEMBER
Any other thoughts on the climate control issue?
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Tuesday, October 15th, 2019 AT 4:35 PM
Tiny
DANNY L
  • EXPERT
Is this an Automatic hvac control system?

Danny-
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Tuesday, October 15th, 2019 AT 11:01 PM
Tiny
BBORTNER21@GMAIL.COM
  • MEMBER
Yes, it has temperature control for drivers side and passenger side.
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Wednesday, October 16th, 2019 AT 4:46 AM
Tiny
STEVE W.
  • EXPERT
The lights are likely the dimmer section of the switch. For the HVAC controls It sounds like a loose power connection. Either at the main connection or a bad solder joint inside it. Do you notice any difference if you hit a bump or if you give the dash a good whack?
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Wednesday, October 16th, 2019 AT 10:11 AM
Tiny
BBORTNER21@GMAIL.COM
  • MEMBER
No it is very odd, it may go several days and not light up (work), then come on. Sometimes when I start out it is not working but 5 - 10 minutes into my commute it lights up. Sometimes when it comes on it is at 60 degrees like the battery was disconnected. So a loose power connection makes sense. The temperature control does not always work, summertime the air only worked part time now that it is getting colder guess what the air always works and the heat is hit or miss.
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Wednesday, October 16th, 2019 AT 11:20 AM
Tiny
STEVE W.
  • EXPERT
Okay, that sounds more like an internal solder joint issue. Not uncommon after most companies switched away from lead based solder. The high tin stuff loves to fail. Do you notice it being better or worse if the temperature changes and causes the board to flex?
You could pull the init out and check the connections to it, It's very easy but don't do it when it is very cold, the entire trim panel just pulls off and if it's cold it can be more easily broken.
You tilt the steering wheel down as far as it will go, then gently start at one side and pull the panel off, there are multiple clips that hold it to the dash. Once it is off the control head comes off with 2 screws and clips.
One thing to do if you disconnect it would be that it needs to be calibrated. For this you simply re-install the parts, then remove the HVAC/ECAS fuse for 20 - 30 seconds. Re-install the fuse and start the truck. Don't touch the controls, the unit will re-calibrate in about a minute. You do this same thing if you put a replacement control unit in, just be sure the replacement matches the options your truck has.
It is possible to test the system further but it requires a scan tool to do much of it.
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Wednesday, October 16th, 2019 AT 3:18 PM

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