I did put an window air conditioner to blow cold air trough the air
exchanger pipes. The air exchanger fan push the cold air upstairs.
This seams to be OK since I am able to adjust cold air flow on each
room, but I would like to know if this would work long term. Is any
possible issue regarding molding in the future?
Effectively I did modify the air exchange installation (during the
summer season) to pull cold air from air conditioner and to push it
upstairs. The air exchanger pipes are from vinyl and part of them are
insulated.