when i turn the ac on high, the car knocks really loud, but if you turn the ac off the knocking goes away, but then returns within seconds but it's not as loud. this is driving me nuts, sounds like something is loose, and it's not the motor because i just put a new motor in the car 2 months ago.
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2006 Toyota Matrix Question: what causes loud knocking when the ac is running?
csubak30 September 14, 2012, 19:25Master
The pulley on the a/c mount has probably got a worn out bearing. Need to replace the pulley and see if the issue is resolved.
Answer #2ziptie12 September 17, 2012, 21:55Master
Check all accessory mounting brackets for loose bolts...................Possibly a bad re-man. engine?