Heater Coolant Shut-Off Valve -N279-, FUNCTION
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Function Mode
- The bracket -2- for the Heater Coolant Shut-Off Valve -N279- -4- is connected to the body via the clip nuts -1- to reduce noise.
- The Heater Coolant Shut-Off Valve -N279- has rubber elements -5- for noise insulation in the openings with which it is secured to the bracket.
- The heater coolant shut-off valve Heater Coolant Shut-Off Valve -N279- is activated from the A/C system control (via the Auxiliary Heater Control Module -J364-) with the parking heater switched off only in certain A/C system settings (for example, in "OFF" mode or if maximum cooling output is requested). The engine speed must be lower than 5, 000 RPM and the coolant temperature must be lower than 95 °C (203 °F).
- Closing the engine coolant circuit to the heater core helps the engine to heat up more quickly when the coolant is cold.
- Closing the engine coolant circuit to the heater core also depends on the engine/transmission version (with certain versions, the circuit is not closed and with other versions, the circuit is closed in conjunction with the heating or cooling of the transmission fluid).
- Depending on the vehicle version and the engine, a check valve with a restrictor can additionally be installed in the coolant circuit. A certain amount of coolant flows through this check valve in the small circuit back to the engine even when the Heater Coolant Shut-Off Valve -N279- is activated. Refer to CONNECTION DIAGRAM - COOLANT HOSES [For engine(s) CTGE, CEUC] or CONNECTION DIAGRAM - COOLANT HOSES [For engine(s) CYNB] or CONNECTION DIAGRAM - COOLANT HOSES [For engine(s) CREC, CREH] or CONNECTION DIAGRAM - COOLANT HOSES [For engine(s) CPNB] .
- The activation of the Heater Coolant Shut-Off Valve -N279- and others is dependent upon the coolant temperature in the engine and in the parking heater when the parking heater is turned on. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
- In the event of a complaint due to poor heating of the passenger compartment in parking heater mode and a complaint due to poor heating of the passenger compartment with the engine running, check the incorporation of the Heater Coolant Shut-Off Valve -N279- into the coolant circuit and the activation by the Auxiliary Heater Control Module -J364-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
- Check the coolant flow direction -arrow- at the check valve -1- with the restrictor, if applicable. Refer to COMPONENT LOCATION OVERVIEW - ENGINE COOLANT CIRCUIT and Vehicle Diagnostic Tester in the "Guided Fault Finding"
function.