1. Identify the Type of Noise: This is crucial. Describe the noise as precisely as possible (e.g., squeal, grinding, rattling, clicking, thumping, whistling). This helps narrow down the possibilities.
2. Check the AC Compressor Clutch:
* Listen Carefully: With the engine running, turn the AC on and off several times. Does the noise start and stop precisely when the compressor clutch engages? If so, the problem is likely *in* or *connected to* the compressor.
* Visual Inspection: Look for any obvious damage to the clutch itself. Is it loose? Is there anything rubbing against it?
* Clutch Engagement: Observe if the clutch is engaging and disengaging smoothly. Hesitation or a jerky action could indicate a problem. A sticking clutch can cause excessive wear and noise.
3. Examine the AC Compressor Pulley:
* Wobble: Check if the pulley wobbles excessively. Play in the pulley bearings will create noise.
* Belt Alignment: Even with a new belt and tensioner, ensure the belt is correctly aligned and tracking properly on the compressor pulley. Misalignment can cause squealing or rubbing.
4. Inspect the Idler Pulley and Other Accessories:
While you've replaced the tensioner, other pulleys in the system (idler pulleys, alternator pulley, power steering pulley) could be worn or damaged and make noise when under the extra load of the AC compressor. Listen carefully with the AC on and off to isolate the source. A pulley bearing failing will often make a high-pitched squeal or whine.
5. Check for Low Refrigerant:
A low refrigerant charge can cause the compressor to work harder and generate unusual noises. While this might not always cause a *direct* mechanical noise, it can strain the system and lead to premature wear. A qualified mechanic can check refrigerant levels and add refrigerant if needed (but only if there are no leaks). Warning: Don't attempt to add refrigerant yourself unless you are experienced with AC systems – improper handling can be dangerous.
6. Consider the Evaporator and Blower Motor:
* Evaporator: While less likely to be the source of *mechanical* noise, a severely restricted evaporator can overload the compressor and contribute to noise. This usually manifests as reduced cooling, though.
* Blower Motor: A worn blower motor can create noise, but this is usually present *regardless* of the AC being on or off.
When to Seek Professional Help:
If you're uncomfortable with any of these checks or can't pinpoint the problem, it's best to take your Jeep to a qualified mechanic specializing in automotive air conditioning. They have the tools and expertise to diagnose and repair the issue properly. Ignoring AC noises can lead to more extensive (and expensive) damage to the compressor or other components.
