Re: Cold Air Return
julia... having warmer temps. on the second level is not unusual since warm air rises ... also if the insulation isn't at a high value would also contribute to this.
However ... because of this .... it's important to have a well balanced heating/cooling air delivery system.
It sounds like the system you have isn't quite balanced properly ... though it's difficult to see over the internet.
Things like improperly sized or poorly located ducting would certainly cause a lot of these kinds of issues. Also poorly fitted ducting ( leaky ) would certainly cause
It may be in your best interest to have a company do a balance test of your system. Basically they would measure the air flow from the supply vents and determine if the return vents are appropriate.
Just a thought.
"" an ounce of perception -- a pound of obscure "