FritoSantana

Hey guys, I’m new here and I didn’t see any threads on this specifically already. Yesterday, I noticed that about 10 seconds after my I start my car (2010 GLK 136,xxx miles) the radiator fan starts spinning on high. Even though I know realistically it isn’t warm enough at the time to warrant the fan spinning. Yesterday my ac worked normally but today my ac isn’t blowing cold air anymore. The last time the radiator fan was spinning like that, it was because I’d blown the ac control module fuse. Once I replaced the fuse, I never had that problem again until now. The ac control module is working normally, it’s just the system itself isn’t blowing cold air. I’m not sure if it’s something as simple as the ac needs to be charged, or if it’s something more. I’m a novice mechanic so I apologize if I’m missing something obvious, but any help is greatly appreciated.

CaliBenzDriver

You're going in the right direction... bad A/C pressure is known to run the fan supersonic wild.

Go ahead and confirm that with your scanner. ECU signals the fan to control its speed.
Look for code and read live data from AAC module.

RiverGoat

I’ve just had the exact same issue with my low-mileage (60k) 2013 GLK. A/C worked great since purchase (Sep ‘22). Got in it a few days ago and the a/c wasn’t blowing. After (fairly superficially) inspecting a few basic things, I disconnected the battery, waited 5 minutes and plugged it back in.
That got the a/c blowing again, but it was blowing hot air. Brought it to a shop, they ran dye to check for a Freon leak, found no leak, turned it back on and the a/c was blowing cold again. Paid $250 and left with working a/c. But I’m not feeling very confident that I won’t run into this again. Curious if you got to the bottom of what was happening with yours.
I’m in Houston where today marks the 38th day over 100deg. Yesterday was 106. I definitely don’t think I should rule out the intense heat having something to do with this.
*editing to add that once I reconnected the battery and the a/c started blowing again, the radiator fan started blowing high and constantly, exactly as yours is.

calder-cay

We're out in Magnolia, so understand the heat wave.

However, I think it depends where the vehicle is parked and the majority of driving, and use of a/c. Our 2014 (87k?) stays in the garage, and driven every 4-5 days to grocery store or others errands, then back to garage (retired couple), so it's rarely out in direct sun/heat for more than a couple hours.

But yea, if you're out and about for way more hours, with a/c on always on full blast, it should be serviced more often.