any known problems with this particuliar make and model year

If it is equipped with the 3.0L OHV V6, ''brown coolant'' has been a problem with these particular vehicles since new. The rust inside has caused deposits to be formed throughout the entire cooling system blocking important passages, including the heater core which would cause a lack of heat concern. Water pump impeller blades have been known to be eaten away by the rust deposits. Fixing this problem would require SEVERAL coolant flushes of each major component including the engine block, the heater core, & ESPECIALLY the radiator. When l say SEVERAL flushes, l mean SEVERAL. Replacing the thermostat & water pump would not hurt at this time if needed. Again, this only applies to vehicles equipped with the 3.0L OHV V6, NOT the 3.0L DOHC 24 valve Duratec V6.

I've seen them burning blower motors because of water intrusion into the housing.

more often than not it is the hoses running to the heater core, it was a common problem and your local ford lincoln mercury dealership should stock the hoses, They will need to know what size 3.0L it is (12valve or 24 valve) FORD BASE PART # IS 18B402