I am looking for any sources for the Minhag of only needing to clean one room in your house for Pesach if you are going to be away for the whole chag.
Chazal obligated each person to search for Chometz on the night before Pesach. [If one leaves town before that time, he is still obligated to search for Chometz the night before he leaves, although no blessing is recited for that search.] In the opinion of many Poskim, the search for Chometz is obligatory whether or not one owns his chometz by the time Pesach arrives, since once the Rabbinic ordinance was enacted, it cannot be abrogated regardless of the circumstances. Consequently, selling the house to a non-Jew does not free one from his personal obligation to search for Chometz.
A solution to this problem is to set aside one room in the house, even a small one, and not sell it to the non-Jew along with the rest of the house. That room should be cleaned for Pesach and thoroughly searched for Chometz on the night before Pesach, with the proper blessing recited for the Bedikah. One who will have already gone out of town by the night before Pesach should follow the same procedure on the night before he leaves – but he may not recite a blessing on the Bedikah.