I have Civic EXI 1999, soundless drive, while i ON the AC button a Zooon ..Zooon sound came from engine bay..sound up & down with accelator position specially in 1st & 2nd gear..but sometime no sound come...and no sound come in 3rd & 4th gear... AC cooling is excellent all the time.
The sound also effect drop in my pick up...plz advise..is it AC compressor Bearing sound..?