The first thing I would check is the coolant level. IT must be full.
IF full, leave blower off and bring to operating temp,
Then turn on blower to high, Is it warmer and then quickly cools off? PArtially plugged heater core.
Feel the heater hoses when at operating temp. Are both hot?
If it is slow to come to temperature and your fuel mileage is worse, the thermostat may be defective.
Tuesday, January 5th, 2010 AT 8:03 PM