Vibrating sound gets worse when AC is on

My car is a 1.8 litre VTEC engine, it makes vibrating sound when at low speed and it gets worse when Air Con is switched on, mainly on co-driver side.

I changed the timing belt a month a go and then this sound started, I took the car back for checking and still the vibrating sound is still there. It vibrates on the dashboard mainly on the co-driver side and gets worse when AC is on. The engine doesn't sound so great either. Kindly let me know what effect this may have on the car or I should not worry.