HVAC display

[plastic orange]

I took my Corvette out to a car show today and noticed the HVAC display was blank. I thought they went dim before going blank to give warning, but no, so looks like removal and soldering is required. I'll do this when things warm up a bit. I've looked at the usual how to sites, and it looks straightforward enough - hopefully. I'll take pics when I'm doing it.

Pete

 

[teamzr1]

Hi Pete
I have fixed several of the HVAC head for the problem you're having, follow this and reflow the solder joints as below
Being surface mounted, chips just use a bit of new solder to reflow the old solder

There is a common failure point for all C5 HVAC controller head in where the LCD screen the output goes dim and in sunlight cannot even be seen
to make adjustments for what you want in HVAC

Replacement HVAC units today costs as much as $600 plus yours as a core but since GM quit using these are harder to find these for sale

Some vendors do have a repair service where you have to mail them the unit and then have the downtime to get the unit back to them
Many charge $75 plus and the cost of round trip shipping
This could take from 1-2 weeks

Here is an example of fixing this command failure point :

There are eight resistor packs, on top they say "241"
Over time due to heat the soldering joints from them crack causing lower voltage to the LCD screen

Take the HVAC unit out of the console, there is only 1 small mounting screen at each end.
Disconnect the wiring harness from the unit
Remove 4 small screws on the back side to crack open the rear and front cases.
Lift up the rear daughter board out of that back case
Turn over and look for eight resisters packs labeled 241
Use a low wattage soldering iron with thin solder
Re-solder both ends of each of the 8 resister packs, do not overheat them
Best is re-solder just one end of each and then let them cool a few minutes and then re solder the other ends
So that is 16 solder joint ends
While the unit is open lift the front daughter board by removing 4 small screws (1 per corner) and there is several LED as lights and the LCD screen and the lens for it and clean them
Reverse the process in putting the HVAC unit back together and then reinstall back into the console
Before installing center console, turn Ign key to ACC and assure LCD now reads clearly

Cost is zero if you have small soldering iron and thin roll of solder, otherwise maybe spent $25 for them and use for other projects

Here is before and after re-soldering was done

NOTE :
To show this, I traced what each wiring pin was for and then temporarily hooked up voltages and ground to make the LCD screen viewable

Not something you need to do

 

[plastic orange]

Thanks for that,

Pete

 

[teamzr1]

Notice how dim the LCD was before I did the repair
and how much brighter it is even in sunlight after I reflow of solder joints

 

[plastic orange]

The display on mine wasn't dim, just disappeared today,

Pete

 

[teamzr1]

Does the HVAC functions work when you click on the buttons ?
The cracked joints could be worse on yours or too dim for you to see them
Have you checked the fuse for HVAC controller ?

 

[plastic orange]

Yes, buttons seem to work ok. The display seemed bright prior to failure though.
Cheers,

Pete

 

[Stingray]

No choice but to try the re-soldering solution and see if it works.

I did mine myself and it worked. I'd say it's a job that requires medium skill with a soldering iron. If in doubt I'd take it to a TV engineer and point him towards the "how to fix C5 HVAC" guides on Youtube etc.

A fair amount of careful dismantling of the car's interior trim is needed to extract the HVAC controller. Again, there are guides on Youtube.

 

[plastic orange]

Cheers, I have a mate who's previous job involved a lot of soldering, but I may just have a go myself.

Pete

 

[plastic orange]

Well, that was a nice easy job, an hour start to finish and all working again. No point in taking pics, as it's all well documented on youtube etc, but thanks for all comments from here,

Cheers,

Pete

 

[teamzr1]

Phil, did they reflow the solder for all the resistor packs I showed in photos above ?

A lot cheaper than those getting suckered into replacing the HVAC head or high dollars and downtime to
send out for repair

 

[plastic orange]

I just re flowed the 8 resistors and it's all working. I did it myself as I wanted it done quickly. Only slight issue was finding a suitable socket to remove the small bolts retaining the circuit board, plus it took me a minute or 2 to work out how to disconnect the cigarette lighter from centre panel (i almost typed fag lighter, but realised that term has a different meaning in the US lol)

Pete