It just blows cold air. Is my thermostat messed up? What else should I check? Thanks.

 

low coolant in radiator/overflow container, clogged heater core, bad tstat, broken blend doors in dash, clogged heater hoses, broken vacuum lines, malfunctioning device on firewall-can't remember the name of the top of my head, hopefully someone will jump in. The other questions are year, mileage, condition, history of radiator flushes, does car overheat or run cold, etc.... Sometimes the outside fresh air **** is in the wrong position-or the controls are broken. Good luck. And remember at least summer is coming soon.

 

also, how is the water pump?

 

^^^^^^^^^^ ........possibly heater core. Sounds like what I went through. No fun