Infiniti G A/C Blowing Hot: Sensor or Something More?

Hey there! I had a similar issue with my 2004 Infiniti M45 last summer. Initially thought it was just low refrigerant, but turned out the AC control unit was failing. The symptoms were exactly like yours intermittent cooling and warm air coming through the vents even when the AC was "on." Took it to my regular Infiniti specialist, and they diagnosed it as a faulty AC control module. They had to replace the entire control unit, and they also found the compressor wasn't engaging properly because of the bad signals from the control module. It was definitely a serious fix since the control unit is pretty complex and needs proper diagnostic equipment. After the repair, the AC has been working perfectly nice cold air and consistent performance. If you're in this situation, I'd strongly recommend finding a specialist who knows Infiniti systems well. These AC issues can be tricky to diagnose correctly without the right experience. Hope this helps with your decision!

Thanks for sharing your experience! That sounds exactly like what I'm dealing with. Do you remember roughly how much the repair set you back? And has everything been running smoothly since the fix, or have you noticed any other issues pop up?

Hey again! Yes, I'd be happy to give you an update! After I got my 2004 M45 fixed, it's been running like a dream. The total bill came to 980€ for fixing the AC control unit, which was definitely a hit to the wallet, but totally worth it for having proper cooling again. And here's some good news they actually found and fixed that heat exchanger temperature sensor issue I mentioned earlier while they were in there. Since the repair, I haven't had a single problem with the AC system it's blowing nice and cold, and everything's working exactly as it should. Just a heads up though these kinds of repairs really need someone who knows what they're doing with Infinitis. The diagnostic equipment alone is pretty specialized. But once it's fixed right, you should be good to go! Let me know if you need anything else always happy to help out a fellow Infiniti owner!

Thanks so much for the detailed info! Actually, I went ahead and took your advice about finding an Infiniti specialist. Found a great shop about 30 minutes from me, and what a difference! Turns out it wasn't just the temperature sensor they found a small leak in the system and a worn-out compressor clutch. The whole thing cost me about 850€, which wasn't as bad as I was expecting after hearing your story. They fixed everything in one day, and the AC is now blasting cold air like it's brand new! Really glad I asked here first saved me from going back to my old mechanic who probably would've just recharged the refrigerant and called it a day. The new shop even gave me a full inspection report and showed me everything they fixed. Think I've finally found my go-to mechanic! Thanks again for pushing me in the right direction. Here's to hoping both our ACs keep running smooth through the summer!