hvac nobs

[Alfa2Evora]

Resurrecting this again, 'my' control knobs haven't illuminated for years until that is a few weeks ago when, without any outside intervention, they suddenly sprang back to life.

All is not 100% though, surprise, surprise. There seems to be some bizarre correlation between the position of the fan control and the intensity and duration of the backlighting for the knobs. With the fan 'off' or on setting #1, the knobs stay fully lit for as long as the journey takes. Put the fan to #2 position though and after about 30 minutes, the illumination starts to diminish until it's a total blackout a further 30 minutes or so later. Position #3 sees the fade start after about 20 minutes with darkness descending after another 20, and position #4 hastens the process to about 20 minutes in total before you're left groping around trying to feel for the little pips,  .

Also, whether it's connected to the illumination issue or not I don't know, the higher the fan speed the hotter the control knob gets - in fact, by the time the lighting has gone out the knob is so hot it's a better source of cabin warmth than the heater unit itself, 

[madmax]

Not sure if this helps at all but when I looked at mine closely, I found that adjusting the dash panel rheostat had a direct result on the brightness of the HVAC panel - and, not surprisingly, there doesn't seem to be a direct correlation to the brightness of the main dash and the brightness of the HVAC controls. On my car I seem to have found an optimum setting so that the heater controls including the little red pips are nicely bright and yet the dash isn't too strongly lit. 

I have to confess it was more by trial and error than any scientific or electronic wizardry but I'm pleased with the result 👍

[Alfa2Evora]

Thanks for the suggestion but the rheostat doesn't seem to have any effect on the HVAC panel, only on the main instrument cluster.

[Alfa2Evora]

In a bizarre twist, without me having done anything to investigate or repair, everything is back working as it should - for now anyway. Knobs and background nicely lit with their intensity controlled by the lighting rheostat and the fan knob, although it does still get a bit warmer, it's not so hot that you can't touch it.  I wonder how long this will last?

Just so I don't get too excited though, the interior roof light which also hadn't worked for years until it was replaced a couple of months back, has again decided to go on strike, . 

[122]

15 hours ago, Alfa2Evora said:

Just so I don't get too excited though, the interior roof light which also hadn't worked for years until it was replaced a couple of months back, has again decided to go on strike, . 

Was the whole unit replaced or just the bulb? If the latter, then the unit may be corroded (as mine was). 

I think the part was about £20 from a Vauxhall dealer.

[Alfa2Evora]

Whole unit replaced, with one in a Vauhall wrapper at £15 on Ebay rather than the identical item in a Lotus wrapper at £72.

Was working fine until the other day then nothing. I'll need to whip it out when I get a moment and see if I can work out what's going on. Footwell lights and door lights are still working so it's not the entire circuit that's gone down.