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X TYPE knocking when AC is on at idle

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middleagecrazy

middleagecrazy

Senior Member
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I have a 2003 X Type, About six months ago there was a knock that developed. At first I thought that it was a serpentine idler but I can not pin point the cause. I do know that there is a tie to the AC compressor because you can turn off the ac and the knock goes away. Any ideas or suggestions will be appreciated.

Anthony
 
head for someone(a shop with a lift) who is able to get the vehicle up in the air for an inspection. Sounds like belt tensioner, but could also be compressor, internal or mounting bolts. Has the vehicle ever been in a collision, or any repairs done on the front of the engine? If so, check those areas.
 
Anthony...a substantial knock or a chattering/dieseling type knock...knocks only at idle or at acceleration/load ..I've seen border line octane levels where the car is fine until additional load like the A/c compressor kicking in then the fuel octane just won't feed em..hence knocking...I'll asume you've tried to run higher octane premium in it...my SUV has a 6 and still requires a blend to keep her happy...

I did also find this on the popular mechanics site if it only does it when the a/c is on:

Knocking noise from air conditioner:
The engine runs well and makes no unusual noises until you turn on the air conditioning. Then you hear a chatter or knocking noise only when the air conditioning is on. The noise will get louder and more noticeable over time.

Possible causes:

The bearings in the air conditioning compressor are bad: Replace air conditioning compressor.

The clutch on the air conditioning compressor is weak or worn: Replace air conditioning compressor clutch.

The air conditioning compressor is bad: Replace air conditioning compressor.

A control valve in the air conditioning system is bad: Replace air conditioning control valves.
 
Hey Anthony...did you get any time yet to figure it out...inquiring minds want to know?
 
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