Originally Posted by Krillah
My '05 Grand Cherokee 5.7L chirps really loud once my AC/Heat is turned on.. Or any interior climate function for that matter.. Is it a idler/pulley?
Also my rear differential sounds like an Apache battle cry at highway speeds.. Could use some guidance!!
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Chirping could be the accessory belt squeaking when under load, failing compressor, failing idler pulley, or just about anything else. It could also be the blower motor itself - is the noise coming from inside or outside?
As to your howling, pinion bearing is a common cause in the rear diff. Does the howling go away if you are on/off the gas? Could also be rear wheel bearings (though they typically sound different when they are loaded and unloaded through turning).
Have you checked your rear diff to ensure proper fluid level and quantity? Howling at speed is one of the first signs of insufficient lubrication. Start with the simple stuff!