Theres 2 hoses in and one hose out. There are two different feeds to the high line heater cores under the dash, I'm guessing one feeds a section of the heater core for the drivers side, and the other does the passenger side with their own hot water supply, and a common return line. There is a small aux coolant pump on the left side of the car near the firewall that pumps hot water from the engine thru the dual temperature control solenoids located right next to the pump. The dual solenoids control the amount of hot water entering each of the two heater cores. Coolant then returns thru the common line and reenters the engine to be reheated. The left two hoses (closest to the left fender- drivers side in NA) are the inlets to the heater cores, the right one (closest to the center of the vehicle)is the common return. If you are trying to completely isolate the heater cores you need to remove the hose from the inlet to the pump, and connect it to the hose on the right most tube coming out of the firewall. You also would need to disable the pump and solenoids to keep from damaging them since they won't have water running thru them to cool and/or lubricate them. Have no idea what kind of fault messages you will get or other issues with the varous controllers doing this. If you have a fuel burning heater you will also need to disable that and the change over valve for it as well.
Thank you MARK for you explanation I’m thinking to do this as one ac technicion suggest it because my ac is not cooling enough and we check the system and everything seems fine picture is the only hoses that I can see and the pump you mentioned
It sounds like the heater is not shutting off completely and therefore the cabin is not cooled as much as it could be. An interesting solution in a country that likely never needs heating except at night? maybe