Electric Fan Failure Causing Avalanche Overheating Issues

Had the exact same issue on my 2008 Chevy Tahoe. I've worked on a few cars before, mostly basic maintenance stuff. The cooling system was acting up just like yours, temperature running high and the electric fan wasn't engaging. After some back and forth with my mechanic, turned out it was just a loose connection at the fan motor plug. There was some corrosion on the terminals too. Total repair was around 95 for cleaning, securing the connection, and testing the cooling system. Pretty straightforward fix, but definitely worth checking before replacing the whole fan motor or temperature control module. Could save you a bunch of money. What engine size do you have in your Avalanche? Also, does your fan ever turn on at all, or is it completely dead? This info would help narrow things down.

Thanks for sharing that experience. Mine's a 5.3L with 133456 KM on the clock. The radiator fan actually never kicks in now, even when the engine's clearly running hot. Already checked the fuses and they look good. I'll definitely look into those electrical connections you mentioned, much rather find a loose wire than need a whole new fan motor. Did your mechanic mention any specific testing process they used to diagnose the vehicle overheating issue? My last service was just 2 months ago and everything was working fine then, so this seems like a sudden failure.

Thanks for those details about your 5.3L. On my Tahoe, the mechanic actually used a diagnostic scanner to check the temperature sensor signals first. When those came back normal, they did a basic power test at the electric fan connection, that's how they spotted our corroded terminals. Since your radiator fan isn't engaging at all and the fuses are good, definitely sounds similar to what I dealt with. My fan also went from working fine to completely dead pretty quickly. The mechanic said electrical issues with these cooling systems often fail suddenly like that, no real warning signs. Quick tip though, while checking those connections, make sure to inspect both the main power and ground wires to the fan motor. In these models, the ground connection can get pretty corroded where it attaches to the frame. My mechanic showed me that even a slightly dirty ground can prevent the electric fan from running properly and cause engine overheating. Worth taking a good look at those points before replacing any major parts. If you're comfortable with basic electrical testing, you could check for power at the fan connector when the engine's warm, just be careful working around a hot engine.

Thanks for the detailed suggestions. Just wanted to update, you were spot on about checking the connections. Found heavy corrosion on the ground wire connection to the frame, plus the main connector was super loose. Cleaned everything up, secured all connections properly, and the radiator fan is working perfectly now. Engine temp staying right where it should be, even in slow traffic. The cooling system is performing like new, no more overheating issues. Saved a bunch of money by checking those electrical connections first instead of jumping straight to replacing the fan motor or control module. Really glad I asked here before heading to the shop. Thanks again for pointing me in the right direction with the fan clutch electrical diagnosis.