I'm looking for some help on cold air returns. I have an older home that has the cold air returns on the outside walls. The house has 1 bdrm down and 2 up. There is a C.A.R in each bedroom, one very large one in living room and one under kitchen cabinets. I haven't seen outside C.A.R.'s before and they seem to allow a lot of cold air into the rooms....when the furnace runs it feels like cool air is actually blowing out......and when furnace isn't running they feel very drafty.

Is there anything I can do with these?? Seeing cold air drops, can I put an elbow type diffuser over these...will that even do anything? Looking for any advise.