2004 Chevy Impala

While driving today all of a sudden the heat stopped working. No air coming out at all. I tried the AC, the defrosters, the floor heat, and nothing came out. When I switch from vent to floor to defrost I can hear a humming noise like it is switching over but the fan never starts. Is this a bad fan motor? I did some searches and resistor came up alot but it seems it would still work somewhat if it was the resistor?

The blower it self could be bad, check for 12v at the connector if ok, the relay/resistor is the usual culprit, up behind the glove box on the blower case. watch for burnt connector at the relay also.

I agree with Maxwedge.

I have a 2005 Impala that had the same issue. You will hear the motorized
vents operate but the air will not flow. On the blower itself which is located under the dash, under the glove box, will have a white connector with a blue and red wire going to it. Or what colors they used in your year.

The resistor is mounted in the plenum. They used plastic welding to hold it in place. Disconnect the connector from the motor and turn the blower switch on high. That will not heat the resistor. Use a meter or test lamp to see if you have 12V present. If you do , then you have a bad motor. A new motor is about 75-80 bucks. That has the fan mounted also. I got lucky with a junk yard motor.

There are 3 10mm hex bolts holding the unit in place. In this time you may want to replace the cabin filter which is on the passenger side under the cowl.

Good luck and keep us posted.
John