There are several reasons for your heater to blow cold air, the heater belnd door being stuck, no thermostat, low coolant, diagnosis is key.
If you have a 3.1 V6, you may need to bleed the coolant system. In front of the engine passenger side, you have a bleeder screw, with the engine off, surge tank cap off, open the valve until coolant flows smoothly, close the valve, check coolant, add if needed.
it's a $5.00 thermastat The problem could also be low coolant level. If the coolant gets too low it will not pass through the heater core and therefore will not heat the cabin air.
You may need to have your heater box inspected. It is possible for the flapper to be jammed or broken. It is a big fix so make sure to check coolant levels and leaks as well.
it wont blow heat itll blow cold air
It doesn't really blow it out it just warms the cold air.
heater core possibly plugged and leaking
The front expansion valve is clogged.
Could be a bad thermostat.
Your heater will blow cold air only.
Low Coolant? Bad thermostat? Heater core plugged or restricted? Heater core airbound? Heater control cable not working?
Do you have a heat pump or Gas Furnace? With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!
bad engine thermastat With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!
engine not warm, low coolant, or stuck thermostat
you would have to see a mechanic about that problem