Read you Declarations, There are to many variables to consider, with out knowing more..

You need to see if the pipes are common elements or your property. 
 
The question is a bit vague because it sounds like they fixed the problem. In fact they probably had a fiduciary duty to fix the problem since a blockage in a drier vent is a real fire hazard.

In our Condo, the unit owner owns and is responsible for maintenance of all HVAC ducts (including air intake and exhaust) and dryer venting

More info please... 
 
Can you prove that the work that the HVAC person did resulted in the new problem? 
 
Did the condominium only arrange the appointment for the HVAC person and have you pay for the service or did they pay too. If they paid then it is likely considered part of the common area, and this is for your property manager and/or trustees to settle with the person who did the work. If you paid, then it is likely your responsibility to get the HVAC service back to fix the work they originally did.

We just changed the board and there was a key floating around so we changed the washer and dryers. But they were from the company that services them. Cost us nothing to have changed. If they are ones you have to put money in then no. But if the association purchased them and they are included in the condo rents then yes.