have a 97' Chevrolet Cavalier and there is something wrong with the...

[pure_evil222]

...heater. would like to know what it would B? It defrosts the windows.. front and back... to a minimal amount on the front.. and then nothing is coming out of the heating vents.. would that be the blower or the core... or something completely different? we filled the coolant.. and then when we change the knob to a different setting we hear a hiss noise.. any ideas?

 

[ryankneale]

From what you describe it's what's called a blend door actuator. This actuator which is controlled by vacuum or and electric motor switches various doors in your vent system. It sounds like yours is not switching to direct the air flow and is stuck in the defrost position.

 

[chuckles951]

It may be that the heater control are not working right. One of the control cables may have broken or had a clip come off.

 

[Charlie]

Check fuses and relays to blower motor. If Ok, then it could be blower motor, blower motor resistor or the control switch.

 

[michael k]

The answer from ryanknea is the correct answer.

 

[saved]

Take it to the Chevy Dealership.