METHOD FOR DEFROSTING AN EXTERNAL HEAT EXCHANGER, WHICH IS OPERATED AS AN AIR HEAT PUMP, OF A COOLING SYSTEM FOR A MOTOR VEHICLE, COOLING SYSTEM, AND MOTOR VEHICLE HAVING SUCH A COOLING SYSTEM

摘要

The invention relates to a method (500) for defrosting an external heat exchanger (18), which is operated as an air heat pump evaporator, of a cooling system (10) for a motor vehicle, the cooling system (10) comprising: a coolant compressor (12) which can be connected or is connected to a primary line (14) and a secondary line (16); an external heat exchanger (18) which is located in the primary line (14); an evaporator (22) which is located in the primary line (14); a heating coil (26) which is located in the secondary line (16); a primary line valve (A4) which is located between the coolant compressor (12) and the external heat exchanger (18) and is closed during operation of the air heat pump; a secondary line valve (A3) which is located between the coolant compressor (12) and the heating coil (26) and is open when the air heat pump is in operation; the method comprising the following steps: closing (S502) the secondary line valve (A3); opening (S503) the primary line valve (A4), so that coolant flows directly from the coolant compressor (12) to the external heat exchanger (18); setting (S504) a pressure level of the coolant on the input side of the external heat exchanger (18) to a target pressure which corresponds to a condensation temperature (Tkond) of the coolant in the following range: 2°C ≤ Tkond ≤ 20°C, in particular 4°C ≤ Tkond ≤ 10°C.