The most likely cause is that your air mix door has malfunctioned, and will not change from ac to heat, but it is possible that your heater core has become blocked, or that there is a water valve in the line that has become stuck.
do you need to remove dashboard in 2003 chevy impala to replace heater core
There are heater-resistance wires in the glass of the back windshield.
the control cable probably came off the connector
Is this a 2003 Pontiac Bonneville? I need this answered for this year and make.
Heater core could be leaking
In the a/c heater core housing under dash, pass. side
you need the special tool its about 30 bucks from snap on
depends. is the fan blowing? if not could be switch. if so you may need to replace the heater core first thing is see if your coolent is low. if it is you will not get any heat
It could be coming from your heater core, may need to repair or replace it.
Probably around $500 or more if you have AC.
It does not use a cable. The heater blend door is operated by a electric motor. The complete dash assembly needs to be removed to gain access to the unit.
Look at the engine temperature gauge. If it goes over 200 degrees, change the thermostat as it is stuck and therefore not allowing coolant to the heater core.