Volvo Repair: AC fast cycling, s80 t6, chaning

Question
My 2000 S80 T6 has the following problem:
When AC is on and stopping in traffic, you can hear something is turning ON and OFF very frequently (Compressor on and off?) Clicking sound less than 30 sec and motor RPM changes too. Please advise. Thanks.

Answer
the A/C does normally cycle.it could be low on freon though causing it to cycle more frequently.the RPM chaning may be the throttle needs cleaned or it needs a software download to help this problem.there was a software upgrade for idle surging with A/C  compressor enguagement