Something must not have went back together correctly when replacing the heater core. Looks like someone has to do the job over again.
blower motors bad check fuse bore replacing
Motor hasseized.
A short.
Did you chech the fuse?
check for a blown fuse that says heater or blower motor
Heater blower motor is defective and locked up, or possible short in the wiring.
If the heater fan is not blowing on a 2001 Chevy S10 Pickup, it is possible that the fuse needs replacing. It is also possible that debris is interfering with the operation of the fan. Could also be, a faulty fan motor, a faulty fan motor speed resistor, a faulty fan motor switch,
The fan motor has a short...change it.
You should check the thermostat and the fuse for the heater.
Fuse, switch, speed resistor or motor.
In the VW T5 van, the fuse for the heater is typically located in the fuse box situated under the dashboard on the driver's side. You can find the specific fuse for the heater by consulting the fuse diagram, which is usually found on the inside cover of the fuse box or in the owner's manual. Make sure to check the appropriate fuse rating to ensure it corresponds with your heater's requirements. If the fuse is blown, replacing it should restore functionality to the heater.
In a Hyundai XG350, the fuse for the heater is typically located in the engine compartment fuse box. You can find the fuse box near the battery. The specific fuse for the heater may be labeled as "Heater" or "HVAC" in the fuse diagram located on the cover of the fuse box or in the owner's manual. Always ensure the vehicle is turned off before checking or replacing any fuses.