Thread: HVAC unit lights are dodgy

Check RAVE - Workshop manual - Heating and ventilation - Repairs - Heater control and fan switch

HVAC head unit doesn't require radio out.
I've removed many times without radio head unit out.

I use two credit card type cards(driver license, old Medicare card ... etc) slim sturdy plastic card of some type.

Slot into thin gap either side of temp control buttons.
Push in and jiggle head unit at the same time.
Head unit won't pop out, but as you eventually hit the side spring clips with the cards(whilst you wriggle head unit) it will pop out and just sit proud of the fascia.
Needs to come out straight on as it has 4 locating pins/lugs near each corner.

Could possibly be the plugs as you predict, but I reckon more likely the globes aren't sitting right.

IIRC, globes are 3 x T5 globes and 3 x (either) T4.2 or T4.7 globes for all of them.

Originally Posted by AK83

HVAC head unit doesn't require radio out.
I've removed many times without radio head unit out.

I use two credit card type cards(driver license, old Medicare card ... etc) slim sturdy plastic card of some type.

Slot into thin gap either side of temp control buttons.
Push in and jiggle head unit at the same time.
Head unit won't pop out, but as you eventually hit the side spring clips with the cards(whilst you wriggle head unit) it will pop out and just sit proud of the fascia.
Needs to come out straight on as it has 4 locating pins/lugs near each corner.

Could possibly be the plugs as you predict, but I reckon more likely the globes aren't sitting right.

IIRC, globes are 3 x T5 globes and 3 x (either) T4.2 or T4.7 globes for all of them.

Thanks for this. Pure genius. It could be the bulbs as if I recall only the switch lights go out.

Originally Posted by Bohica

Thanks for this. Pure genius. It could be the bulbs as if I recall only the switch lights go out.

I tried to find my spare head unit, have no idea where it went to double check it all.
I have the old bulbs in a small bag to remind .. but I used LEDs for my project D2 .. so much brighter too.
Once the head unit is off, you unscrew the rear cover to get to the bulbs.

If you decide to replace the bulbs, the old ones will probably have the green plastic sleeve over them(all mine do).
I got green LEDs to match everything else.
Unlike the dash lights, I think from memory you can change the colour if you prefer too.
Dash has a green silkscreen within, whereas the HVAC unit doesn't and will be the colour of your bulbs.

Are you speaking about the old style heater control unit not the digital one ?

This is the digital one.

yep D2 style.

20201009_100148_sml.jpg

Red arrows are display globes. T5 come in plastic holders. Becasue I did mine years ago, can't remember exactly but I don't think the T5 globes will come out of the holders easily. I have the globes but not the holders for some reason.
Those plastic holders tho don't fit into the green arrow spots, as they're too large.

I think the green arrow globe slots are T4.2(maybe) possibly T4.7 type. I know LR have part Nos too, but you can easily get globes off ebay(I did) as long as they fit. Like I said B4, I got LEDs.
You need a flat screw driver to remove the T4.2(T4.7) globes for sure. The green arrow slots are the switches lighting.

With your subsequent reply, that the switches lights go out, it could be a connector.
Note that when you pull the rear cover off(as in photo) you have a small ribbon cable to deal with. Many toys and electronics devices use these types of cables.
If you never dealt with them before: move the rear cover like in the photo, do not pull on the cable. In that posi it has enough flex not to damage it.
Note the white rim on the cable connector on the PCB. Use your finger nails, or a fine tip tool(screw driver, or pliers) pull the white rim area upwards, it'll release the cable .. and it should pop off and out.
Check the contact tracks on the ribbon cable for guff(corrosion or dullness) clean with alcohol or rubber eraser or whatever electrical cleaner if you have any.
This could be a reason why your switch lights are intermittent.
Less likely all 3 globes are playing up.

When putting it together again, pop the ribbon cable into it's slot, use the blue tab on it to push it into slot nicely and then push the plastic rim back down. Plastic rim locks it into place.
I reckon you probably know all this, but it's still easier to post it all .. just in case.

If it were the display bulbs acting up it could be the bulb holders springy contact design losing tension. I had this issue with my dads Pug 307 a while ago.
The T4.2/T4.7 bulb holder design is a bit more positive acting, less likely to be an intermittent connection.