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Bad Bearing, Alternator, Serpentine Belt, A/C Compressor Belt?

I have a 2002 Toyota Echo. 2 months ago it appeared that my a/c compressor was on the fritz and was toggling on and off and blowing mostly warm air. I took it to a mechanic and they filled it with new freon, ran diagnostics (which tested fine) and sent me on my way. Within a mile the a/c was blowing warm air again. I took it back and eventually the mechanic told me that it appeared to be a bad relay for the a/c compressor. So he proceeded to swap my horn relay with my a/c relay to get the a/c working again, but my horn naturally stopped working. The a/c began working properly and 2 months later is going strong, but almost immediately (give or a take a few days) following his quick fix, I began to hear a growling churning like noise around the alternator area that made my car sound like it was dying. It is getting increasingly worse, but sometimes is absent altogether for short periods of time. It increases when I accelerate or toggle the a/c on and off, but it is pretty constant. Two mechanics have (just by listening) stated that it sounds like a bad bearing in the alternator, but research seems to indicate that the noise could be caused by a bead serp. belt, a/c compressor belt, or a bad bearing within the alternator. Yesterday, I bought a new relay for the a/c and returned the original relay for the horn back to the horn slot. I thought the sound was gone at first, but now it just seems worse or about the same.

I am trying to avoid paying for the most expensive solution first.

The relay is not going to do anything to the noise. You need the horn more than the AC IMO, it is a safety issue.

Back to the noise, it could be any of the items driven by the belt, or just an old belt. You will have to either change the most suspicious item yourself and take it from there, or find a mechanic you trust and let them fix it for you. It will cost you money, but I don’t think postponing it is going to be cheaper, nor is a new car.