Engine noise

Good afternoon,

Remove the drive belt and start it and see if it is still there.

It sounds like a bearing that is belt driven.

Roy

It looks like the same video? Here is a guide to help walk you through the belt removal with diagrams below to show you how on your car:

https://www.2carpros.com/articles/replace-serpentine-belt

and

https://www.2carpros.com/diagrams/jeep/cherokee/1999

Please run down these guides and report back.

Try spinning the pulleys one by one until you hear the sound. That will tell you the failure.

Keep us updated.

Roy

Then most likely the Ac compressor front bearing is seized.

You need to replace the AC compressor.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Roy

WARNING: REVIEW THE WARNINGS AND CAUTIONS BEFORE PERFORMING THE FOLLOWING OPERATION.

REMOVAL
1. Recover the refrigerant from the refrigerant system. See Refrigerant Recovery for the procedures.
2. Disconnect and isolate the battery negative cable.
3. Remove the serpentine drive belt.
4. Unplug the compressor clutch coil wire harness connector.
6. Remove the suction and discharge refrigerant line manifold from the compressor. See Suction and Discharge Line for the procedures. Install plugs in, or tape over all of the opened refrigerant fittings.

Compressor Remove/Install
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7. Remove the four bolts that secure the compressor to the mounting bracket.
8. Remove the compressor from the mounting bracket.

INSTALLATION

NOTE: If a replacement compressor is being installed, be certain to check the refrigerant oil level. See Refrigerant Oil Level for the procedures. Use only refrigerant oil of the type recommended for the compressor in the vehicle.

1. Install the compressor to the mounting bracket. Tighten the four mounting bolts as follows: - 27 N.m (20 ft lbs)
2. Remove the tape or plugs from all of the opened refrigerant line fittings. Install the suction and discharge line manifold to the compressor. See Suction and Discharge Line for the procedures.
3. Install the serpentine drive belt.
4. Plug in the compressor clutch coil wire harness connector.
5. Connect the battery negative cable.
6. Evacuate the refrigerant system. See Refrigerant System Evacuate for the procedures.
7. Charge the refrigerant system. See Refrigerant System Charge for the procedures.

Here is the link to help step by step to replace the compressor:

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Please let us know what happens.