so the cold season is approching. my 98' XJ when i turn on the heater or the A/C my engine starts to cry at the same rate as the idle speed, my first thought was a serpentine belt. replaced it same problem, i can rev the motor untill it gets a little warmer and it goes away.. any suggestions?? open to ideas or thoughts. thanks...

 

Sounds like a pully bearing.

 

im not sure which pulley bearing.