There are several reasons. The most common is the blower motor resistor. This can be found in the passenger's foot area. It is mounted in the heater box, and has one electrical connector. The second most common cause is the blower motor itself failed. The third most common cause is the heater control unit in the dashboard ( the thing with the knobs you turn). This is all assuming that you have checked the fuses which are located in the interior fuse panel.
heater core
One reason a 2004 Monte Carlo heater motor blower may not work is low coolant. You can check the coolant level after the car has been turned off.
how do you change a heater core on a 2003 ss Monte Carlo
How do you install a new heater core on a 1979 chevy monte carlo?
How do you bipass a 2004 monti carlo heater hose
Under the dash
On the passenger side on the firewall.
My dashpanel lights stopped working in your Chevy Monte Carlo ss 2001 what could the problem be
Your heater core is likely bad
They are on the backside of the engine and go into the firewall.jd
Mine is, but I'm not sure how to fix it.
Yes, Monte Carlo is in Monaco.