A/C has surging air flow on 1998 Volvo S70

I just started having problems with my A/C. It surges when blowing the air out of the vents. The air is cold, but the air may not blow at all for a while then all of a sudden air will come out at full force then after a few seconds it will quit or almost quit blowing again. Any idea of what the fix would be?

Asked by for the 1998 Volvo S70
Have a qualified shop check the fan speed control resistor system. Speed in controlled by resistance thru these units and may have faulty control or loose connection. If have had recent work in the dash area it may have been unplugged and when plugged back in the pin can push out of connector and make intermittent connection/resistance problems. Good luck.