Heater core or the associated pipework - It may be no more than a rubber hose. Depends on the car how complex, some are easy, some are a real 'fiddle' to get out but It's not 'that' major. Quick fix is as 'd' suggested.

Only an Idiot would "scrap" a car on the strength of a heater core !!

heater core leaking , quick fix but no heat , engine compartment rear -find two rubber hoses (most often on passenger side) disconnect hoses at firewall , using a hose connecter and some clamps connect the two hose ends together (by passing the heater core ) or remove one hose completely- connect the remaining hose heater core end to nipple on engine making a loop , make sure hose does not contact moving or hot exhaust parts

The heater core is located on the firewall, just opposite the passenger seat. Chances are the core or a hose leading to the heater core is leaking.

Hi so that does suggest the heater matrix has a leak the heater inside the car has a leak. as it is so expensive to replace then time to scrap the car. as the cost alone will kill it.

heater matrix leaking