1995 Ford Aerostar Rear Vents

Probably a clogged rear(auxillary) heater core, radiator shop can try high pressure flush, or you can buy a Prestone flush kit, install the Tee in the rear cores heater hose, clamp off the end toward the front, dissconnect and clamp the return hose, and flush by turning on the garden hose, watch for any crud to come out of the core, the radiator shop can do a way better job of this, and would be worth the money!