Volvo Repair: A/C on 98 Volvo S70 T5, volvo s70, c unit

Question
a/c works intermittently.  unit has been replaced twice-- once by
Volvo, once by local shop.  lights on a/c unit will blink on and off
when it's not operational (blower starts up for a second or two then
conks out).  air intake port has been replaced as well
as the thermostat.  

Additionally, when it is working, it emits an unpleasant smell and I
don't even want it on!  any idea on what could be causing the
sporadic operation and/or the bad odor situation?

thanks

Answer
Hi Ben.
   Replaced TWICE!!..To me it seems as though the problem has never really gone away..Has system been properly tested for leaks in A/C system?
           SMELL?...only a few items to consider...mold or leaky heater core....If it is mold...spray some Lysol disinfectent...the kind that smells good...into A/C unit as it draws air from the air intake.
           Unlikely that the heater is leaky.
          Maybe...just maybe.. someone planted a piece of Gorgonzola in the A/C duct....it has been known to happen.
                      Good luck,
                                Bilbo