Praise be to Allah.
It is permissible for the pilgrim in ihram to do ghusl for the sake of cleanliness, because it is proven that the Prophet (blessings and peace of Allah be upon him) did ghusl when he was in ihram. And it is permissible for the pilgrim in ihram to change his ihram garments for cleaner or newer ones. It is also permissible for him to enjoy using air conditioning and other means of comfort. End quote.
Majmoo’ Fataawa Ibn ‘Uthaymeen, 22/144