Hello all,
Is it possible to replace this circuit board without replacing the whole HVAC panel?
20241006_192022.jpg
The board has a crack in it which has broken the circuit to the rear demister button and light. This happened where the little tab on the plastic that covers this meets the edge of the board - you can just about make it out in this photo
I've read that the cables for the HVAC controls can be a real pain to re-attach so I'm not very keen to get into that. One option is to solder wire on to the rear of the board while it's in place to bridge the broken connections, but I'm also wary of bringing a hot soldering iron into the car where it could badly damage plastics, seats, etc if accidentally dropped. So if the board can be replaced without having to deal with the HVAC cables then that would be much preferable
Thanks!
The ribbon cable can be unplugged, I'm pretty sure. I disconnected it accidentally once...
Looking at it from underneath, it looks like you would need to remove it to get at all the electronics?
(https://i.imgur.com/TkDWTIm.jpg)
They are certainly fiddly to reconnect the cables to the hvac control knobs, they are stiff wire cables with a kink in them which just goes through a hole, then you put the outer cable into place up to the stop and close the metal clip to hold the cable in place. This gets harder the more of the cables you attach as you has less room to work with!
The 3 cables are all different;
(https://i.imgur.com/4rb9n62.jpg)
(https://i.imgur.com/FaFkfnb.jpg)
This one is probably the hardest;
(https://i.imgur.com/UByiVAK.jpg)
Take some reference pictures before you disassemble them just in case..
If you take it apart, this is what you get;
(https://i.imgur.com/EWrnP3K.jpg)
(https://i.imgur.com/FTyzXFu.jpg)
(https://i.imgur.com/Pik7UCQ.jpg)
So basically, you are going to have to take it out!
Thanks for the photos - very helpful
That looks like a miserable job, so I think I'll attempt to bridge the connections with some soldered wire
Quote from: Gaz mr-s on October 7, 2024, 10:47The ribbon cable can be unplugged, I'm pretty sure. I disconnected it accidentally once...
btw if this is actually the case then I'm very interested, but as far as I can see it's soldered onto the pcb? And wherever it connects to the HVAC control unit is out of sight and reach
I suppose one option would be to desolder the PCB from the ribbon and solder a replacement PCB back on, but that seems like more work and I've always found desoldering to be a tricky enough business to do cleanly
Surely it's so much easier to buy a cheap used one from J-Spec, or similar?
Quote from: Alex Knight on October 8, 2024, 13:19Surely it's so much easier to buy a cheap used one from J-Spec, or similar?
It would be, if it wasn't sodlered in and replacing it with a cheap used one didn't involve removing the whole HVAC control unit, which itself involves unhooking the various cables and other gubbins behind it and hooking it all back up again to the new one, and which is a known nightmare job - hence the photos and discussion above
..
I was referring to the whole HVAC unit.
Cheap as chips second hand, and it's only a few cables etc.
How hard can it really be to replace?
https://www.mr2roc.org/index.php?topic=72198.0
Quote from: Alex Knight on October 8, 2024, 16:43I was referring to the whole HVAC unit.
Cheap as chips second hand, and it's only a few cables etc.
How hard can it really be to replace?
https://www.mr2roc.org/index.php?topic=72198.0
Everything I've ever read about this - which is quite a bit over the years as I've considered and then abandoned the idea of removing the dash to work on it a few times - suggests that it's a deceptively and annoying difficult job. Significantly more difficult, at least, than soldering in a couple of bits of wire - which anyone with a soldering iron and rudimentary skills could do in about 5 minutes. As, again, indicated by the above discussion.
I'd totally unsolder that and swap it over. Just need a good sucker and some pre fluxed braid. Nice little job that it. And if you arn't confident in doing it, post it over to me and I'll do you a real nice job totally free that will look like factory work.
Quote from: simonrobinson on October 9, 2024, 08:59I'd totally unsolder that and swap it over. Just need a good sucker and some pre fluxed braid. Nice little job that it. And if you arn't confident in doing it, post it over to me and I'll do you a real nice job totally free that will look like factory work.
The offer is appreciated (thanks!) but getting it out to post to you would involve...removing the HVAC panel and dealing with the cables (which is what I'm most trying to avoid!)
I'm happy enough to get the soldering iron out and do this myself, the point of this thread was simply to ask whether there was a way to detach and replace the PCB without needing that (and without having to get into the HVAC cables)
The answer is no, there is not. Thankfully it's not a big job to fix with a soldering iron