Caution, ...authorized to make such exterior common area repairs.
Caution, it's very unlikely that you are legally authorized to make such exterior common area repairs yourself, or do the hiring of a contractor, as you do not own the exterior of your building (the building Envelope is common area), you only own a percentage of it... You could actually open yourself to legal action by the association... Carefully Read your CC&R's!!!
As Our Association President (and lots of rain here), it's not just your shingles that I'm worried about.. it's the potential rot in the substructure (also common area) that may lead to a huge hidden expense if not detected and repaired properly. All of this whether major or minor is the responsibility of the Association. Keep written records of all communications regarding your written requests for repair. If you have not made any written requests for repair as of yet do so immediately, because without them you may not have a legal leg to stand on.
If your association has professional management, contact them directly because they quite often are more responsive than an association board, and may be able to convince the board to expedite your repairs as an emergency repair. Do emphasize the rot potential... And finally if you can get no satisfaction, I'd recommend having an attorney or proper legal counsel write a carefully crafted letter reminding the association exactly what the association's responsibility is and demand the specific performance of repairing your building, the specific repair of which is impacting the sale of your unit.
Do remember that these things do take a little time as the Board is most likely a group of uncompensated relatively inexperienced Volunteers... so if you must scream and shout, try to direct your frustration at the Management Company who should be the ones to contact and hire the contractors for the repair once they get the "go ahead" by the board.
President, Home Owner's Association
Horizon View Condominiums