Honda NBox AC Trouble: Control Valve or Something Else?

Hey there! I've got some experience with car repairs , and I actually faced a similar AC issue with my 2017 Honda Jazz. My mechanic found a refrigerant leak in the AC system, and I also had warm air coming out. Took it to my trusted workshop where they diagnosed the problem with a leak detector, turns out there was a leak in the evaporator unit. The whole repair included replacing the evaporator, recharging the system with fresh refrigerant, and replacing a few seals. Cost me around 495 Euro, but it was worth it as the AC's been working perfectly since then. Before I share more specific details, could you tell me if you're noticing any water dripping under your car or any unusual smells from the vents? Also, when was the last time you had your AC serviced? These details would help understand if you're dealing with the same issue I had. If it helps, the Jazz uses a pretty similar AC system to your NBox, so the symptoms and fixes are often comparable.

Thanks for sharing your experience! I'm having the exact same symptoms you described. My NBox has 169499 KM on the odometer, and I actually had the AC serviced during my last maintenance about 3 months ago. I haven't noticed any water dripping, but there is a slight musty smell when I first turn on the AC. You know what's weird though? The AC works fine in the morning but gets progressively worse throughout the day. I'm hoping it's just a refrigerant issue like yours and not something more serious. Was your Jazz acting the same way before you got it fixed?

Hey again! Yeah, that musty smell and the AC performance declining throughout the day, that's exactly what I experienced with my Jazz! The symptoms are so similar, it's like déjà vu. My Jazz had about 155000 KM when this happened, so pretty close to your mileage. The weird thing about mine was also that it worked better in the morning and got worse as the day went on. My mechanic explained that this happens because refrigerant leaks are often tiny, and the system can still partially work when it's cooler outside. Since you mentioned having your AC serviced 3 months ago, it's possible they just topped up the refrigerant without finding the actual leak. That's what happened to me initially, got it serviced, worked great for a few months, then started acting up again. The musty smell could be related to moisture buildup in the system due to the leak. I'd definitely recommend getting it checked specifically for leaks. When they fixed my Jazz, they used this UV dye in the system to pinpoint the exact location of the leak. Way better than just guessing or repeatedly topping up the refrigerant. Would you like me to share more details about the diagnostic process they used on my car? It might help you know what to expect when you take yours in.

Oh wow, that's super helpful! Yes, please share more about the diagnostic process! I think you're right about the refrigerant top-up during my last service, they probably didn't check thoroughly for leaks. It makes total sense about the temperature affecting the performance too, I was wondering why it worked better in the morning! I'll definitely ask my mechanic about using that UV dye method you mentioned. Honestly, I'm actually relieved hearing your experience because I was worried it might be something more serious like a compressor failure. The repair cost doesn't sound too bad either, I was mentally preparing for something much worse! Thanks so much for taking the time to explain everything. I'm going to book my car in next week and specifically ask them to check for leaks. Really appreciate your help with this!