There is a Vent on the roof for the fridge (above the fridge). You should start by checking the caulk there as well as the plastic cover for any cracks.
You should always be very careful when walking on the roof of your coach. If you find any 'soft' spots then there may have been a leak for some time. If you are uncomfortable with going up on the roof, you should consider taking the coach to an RV service center and have them inspect and do the work.
2006 Fleetwood Pace Arrow 37C
Mods: EEZRV Products TPMS, Cobra 29LX 50th Anniversary CB radio with Firestik NGP Antenna, Self contained sewer hose