Anyone with a P1 should consider replacing the heater hoses before they fail. Same thing with the radiator hose above the transmission. The plastic T connect will crack/leak. The coolant bottle will crack open due to age, heat and pressure. Replace if original. There is not any coolant level sensor on any P1 Volvo. Parts pics are from ipdusa.com 0EPKfo4.

volvo v50 heater not working