Ignition sound/rattle at low RPM's

Hi,

My car listed above is a Toyota IST 1.3CC VVTI. (NCP60).
it has small rattling/ ignition sound at low rpm's. It is not regularly happened but. I notice it sounds when gear shifts with low rpm's. When at highway speed of 100 kmph, it comes. Same stage if overdrive off. No sound noticed.
And also I have notice A/C clutch gives some horrible sound. I have asked mechanic to check and he has tied up the belts. Now less A/C clutch sound comes different speeds.

Is the A/C clutch sound is the reason for ignition sound or all these are two related things.

I have checked VVTI solenoid and engine sludge. All are clear.

Thanks.