Allah kher, ap ko bta du apne zrai se ke mechanics ki mafia bani hwi he, same is happening in isb/rwp, when you visit mechanic they say your engine is dead and need to replace, check proper mechanic, you might need to change your compressor or there might be wiriring issue, i faced this issue in my vitz and actually the ac wiring was connected with gear so that when you move to D and R mode, it starts shaking.
Also the compressor might be faulty and it might be causng this problem.
But be aware that there is a big mafia of mechanics that is growing these days, they have connections, they will tell you to change engine...dont do it...