Over the course of DeLorean production, there are five (5) known, different, HVAC panel decals used on the cars. I have been able to locate photographs of all five and I've displayed the photos below in what I feel is "reverse chronological order". Read on to learn more...
This one pictured above is perhaps the most common. It appears to have been used towards the end of production, and indeed, is the only style that remains available as an NOS (new old stock) part. UPDATED MARCH 2017 - NOS labels are no longer available though the style BELOW has been reproduced by DMC (Texas).
This one (above), is very similar to the one above, but the white outlines around the red/blue temperature knob on the left side are missing, the typestyles are slightly different, and the icon for the "defrost" indicator light is in added in white.
Above we see another version, with white outlines around everything and no icon for the defroster.
And, what I believe is the second one used in production is shown above. Again, outlines around everything, but more details have been added to the three indicator lights across the bottom in the middle. You see words added for the "Cooling Fan Fail", "Rear Def." and "Lock Doors".
Finally, what I believe is the FIRST decal used is one that is ALL BLACK in appearance, with the colors and indicators underneath. The flash in this photo allows the colors underneath to be seen, but without that, it would appear to be all black. Special thanks to Tony Swann, who provided this photo and is a noted collector of 500-series VIN cars. Tony is also well-versed in the unique production quirks of these early cars, and notes that this photo was taken of VIN 500, now in the Crawford Auto Aviation Collection in Cleveland, Ohio.
The HVAC panel is backlit with four incandescent bulbs (plus the three for the indicator lights). On a stock, production, car the four lights are illuminated anytime the key is on, regardless of whether or not the running lights or headlights are on. So, unless the car has been modified, anytime the key is on, engine running or not, day or night, these lights are on.
The earliest decal was designed to allow these lights to illuminate all the controls from behind. It would've looked cool had it worked, these controls coming at you in living color from a solid black panel (see Note #1 near the top center) in the drawing above. Unfortunately, the technology wasn't there yet and people couldn't see anything unless it was at night, and even that was iffy.
As you can see above, one of the items on the 12 page, 162 item QAC checklist (download one here - courtesy of the DeLorean Museum) was "Install A/C control decal on console". This jibes with the story that the early ones were replaced at the QAC with one that was more legible. Company records indicate there were at least two suppliers of these in the USA, and purchase orders for 1,ooo of them that were delivered in late October of 1981.
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