July 9, 20169 yr Hello all! First post here. I have a weird issue relating to my A/C. My car runs great with the A/C off, no weird sounds or anything of note. With the A/C on however, while accelerating around 3000+RPM, the car has what i can only describe as a mechanical "moaning". It climbs with rpm up to a point and upon clutching, it will drop off with the drop in RPM. At first it was more of a rattling similar to what ive heard in some other cars with no A/C problems but has now morphed into this. The weirdest thing is that the A/C still works perfectly. This is baffling me and wondered if anyone has any ideas. My first instinct is that its the compressor/clutch or one of the belt idlers. What do you guys think? Ill try and get a sound clip as soon as i can. Thanks in advabce!
July 9, 20169 yr You'll need a helper to rev the engine up while you listen around under the hood for the source of the noise. A mechanics stethoscope will narrow it down quickly. If you don't have a stethoscope you can use a long screwdriver. Compressors make some noise anyway, but its hard to say if yours is normal or abnormal. It just could be a failing tensioner for the AC belt. If the noise is coming from the compressor, and has been growing louder, then its likely internal damage in the compressor. It may not even be the compressor. When the AC is running there's an extra 30-40 amps load on the alternator between running the radiator fans, blower fan, and AC compressor clutch. Higher load could cause the alternator to make noise. Could also be a loose heat sheild on the exhaust that only rattles when the engine is under certain load conditions.
July 9, 20169 yr Author Thanks Tax for the ideas. Ill have to start poking around. Texan, I had it recharged recently. Maybe it was overcharged?
July 10, 20169 yr likely - many folks report a hooting noise or similar when the system is overcharged.
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