I have carrier forced air heating system (Upflow furnace). There are two heat register in the living room and one in the kitchen that actually are not working (no heat is coming out from those register but sometimes I can feel little cold air draft). All other register are working fine.
I called an HVAC technician to have him look into it. He checked the furnace and as per him furnace is working fine. He popped a mirror with flash light and try to look into the ducts and he could not found any blockage. As per him nothing is blocking inside the duct he checked the flapper on the duct work and it was fully open. He increased blower speed (by exchanging red and black wire) so that air can get more push and told me to reverse the wires back to the original position in summer.
Still there is no hot air coming out from those register..finally I have been told that it could a crushed pipe (duct) in the slab which will take thousands of dollar to replace.
I just bought this home four months ago and not sure what should I do now.