My wife drives a 1997 Explorer XLT AWD, 5.0. Recently the heater stopped w orking at all although the AC is fine. I thought it was a clogged heater core and back flushed it and nothing but clean water & antifreeze came out, reversed the hose and flushed in the forward direction, same result. Next, I purchased a new Motorcraft heater valve and installed it today. Seems t o be working properly and there is hot water prior to the valve and after t he valve going into the firewall (checked by feeling hoses). Still no heat. (fan works properly as do the various direction of air flow-floor, both, vents etc.). Any suggestions a s the next step will be greatly appreciated.