Discovery HVAC Issues: Heating & Mirror Defrost Problems

Hi there! I've got some experience working on cars (moderate DIY level). I had a similar issue with my 2019 Range Rover Sport diesel last winter. At first, I thought it was the climate control unit, but it turned out to be just a faulty cable connection. My local workshop found that some wires connected to the HVAC system had corroded, affecting both the heating/cooling and the mirror defrost functions. Got it fixed for about 155 Euro, mostly labor costs since they had to trace the connection issue through several components. The repair was pretty straightforward once they found the problem spot. Before I can give more specific advice, have you noticed any other electrical issues? Does your dashboard show any warning lights? When exactly did the problem start? BTW, I've seen similar problems in other Land Rover models too, including the Discovery series. Let me know those details, and I might be able to point you in a more specific direction!

Thanks for your detailed reply! My 2021 Discovery (119485 KM) had its latest service about 2 months ago, and these issues started just last week. No warning lights on the dashboard, but I've noticed the climate control buttons feel a bit unresponsive sometimes. I thought I should mention that occasionally there's a slight clicking sound from behind the dashboard when I switch between heating and cooling modes. I checked the fuses myself but they all seem fine. Your corrosion theory sounds interesting, especially since both the cabin climate and mirrors are affected. I'll definitely get those connections checked out. Did your repair hold up well afterward? I'm hoping it's something similarly straightforward and not a major component failure!

Hey again! Glad to help further with this. Yeah, those clicking sounds you're describing sound really familiar, that's exactly what I heard in my Range Rover before getting it fixed. The unresponsive buttons are definitely another red flag that reminds me of my situation. The repair on my car has held up great, no issues for over a year now. Since you mentioned the clicking sound and button response issues, I'm even more convinced it's similar to what I dealt with. My mechanic explained that the corrosion usually starts small but can spread if not addressed, which is why both the climate control and mirror defrost get affected, they share some of the same wiring paths. One quick thing you could check (I did this before taking mine in), try pressing the AUTO climate button while holding the recirculation button for about 5 seconds. Sometimes this resets the system. It didn't solve my problem completely but might help diagnose if it's electrical or mechanical. Just keep in mind though, even though our symptoms match, these cars can be tricky. My repair was straightforward, but I'd still recommend getting it checked soon before winter really kicks in. Those mirror defrosters are no joke when you need them! Let me know what you find out, I'm curious if it turns out to be the same issue as mine.

I'll complete the conversation from's perspective: Thanks so much for the extra tips! I actually tried the AUTO and recirculation button reset you suggested, no luck unfortunately, but good to know about that trick for future reference. I've booked it in at a workshop for next week. You've given me some confidence it might not be as serious as I initially feared. Really helpful to know your repair has lasted well over a year, that's reassuring. I was worried I might be looking at replacing the entire climate control unit! The clicking sound is getting a bit more frequent now, so I'm glad I'm getting it checked soon. I'll definitely ask them to inspect those wiring connections first before looking at more expensive fixes. Will let you know how it turns out, hopefully it'll be a similar straightforward fix like yours was. Really appreciate you sharing your experience!