Is the popping sound kind of metallic, like you could make by striking a sheet of metal with your hand or fingers, or is it something sharper and more like a miniature fire cracker ? If the former, I would suspect expanding/contracting ductwork. If the latter, it might be something electrical, and should be pinpointed and investigated asap. JMHO
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.