I recently bought a used 2000 model mazda protégé/323 .it has done 130000 kms. During idle when the a/c compressor gets on, the car vibrates like hell for a couple of seconds. This happens every time the compressor picks up. What could be wrong? My mechanic says its common for all the cars, but I would like to know if I can reduce the intensity of the vibration?

 

that would be my guess. new motor mounts

 

you may want to check to see if your clutch on your ac is going bad. Get in the Car and have someone watch from the outside and put the car in gear forward, and reverse, with the brake applied heaveily, does the motor twist forward or backward alot?
Check your lower pull have the car running be careful and look at lower pulls to see if they are warped. the alternator might not be inline or the power steering pump may be off. there are a lot of littel things. does the car shift really hard(automatic) with a clunk?

This also may be a problem of vibration if the car drops RPM to low during ac cycle times. The load on the engine of the ac compressor robbing power.