Travel credit use to get full refund

I am positive that I booked a flight with full refund to original payment not, flight credit. Went to cancel and says only to flight credits. Can I use those flight credit to buy a fully refundable ticket then cancel to get the full amount back? Like, $500 flight credit towards a $1000 flight, use the flight credit and buy the remaining $500 on CC, then cancel full amount to get the $1000 back? Does that work?