2004 Dodge Dakota 177k miles... AC worked fine just a couple days ago, now it literally sounds like a train horn. Extremely extremely loud, not just the screeching or scraping noises I see in other people's videos. No noise or other symptoms if the AC is left off. I can't see any metal shavings or anything visually wrong with the compressor.

How would I go about diagnosing this?

 

Actually I think it's just the blower motor whoops... sorry for clogging up the forum.

 

No worries. Swap out the blower. The bearings in those DO get LOUD when they go.

 

In my gen 3 ram it was a pecan hull in the blower. Also had a broken fin. the new blower is not as efficient though.

 

Unfortunately I was wrong and it wasn’t the blower motor after replacing it. It was happening somewhat intermittently but now it’s more or less full time train horn screeching noises (takes a minute after turning the AC on sometimes.)

And the AC doesn’t get cold at ALL despite working well recently. Some kind of valve broken maybe?

 

I should probably also mention that there’s a burning smell when I turn on the AC.

 

So what's makin' all the noise? Where is it coming from? If it's the compressor, what you are smelling is likely the belt burning.