Heater Coolant Shut-Off Valve -N279-, Function
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2015 Audi RS 7, 2015 Audi A7 Quattro, 2014 Audi S7, 2014 Audi RS 7, and 2014 Audi A7 Quattro. However, it is still accessible from the selected car via links, so may be relevant.
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 -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 RPM must be lower than 5, 000/min and the coolant temperature must be lower than 95 °C (203 °F).
- By turning off the engine coolant circuit to the A/C heater core, the amount of time it takes to heat up the engine when the coolant is cold quickens.
- The shutting off of the engine coolant circuit to the A/C heat exchanger also depends on the engine/transmission version (on certain versions, the shut off does not occur, while on other versions the shut off is performed in connection with the heating or cooling of the transmission oil).
- 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 FOR ENGINE(S) CTUA & CGXB - COOLING SYSTEM , FOR ENGINE(S) CPNB - COOLING SYSTEM or FOR ENGINE(S) CEUC & CRDB - COOLING SYSTEM .
- The activation of the Heater Coolant Shut-Off Valve -N279- and others is dependent upon the coolant temperature in the engine and in the auxiliary heater when the auxiliary 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 - COOLANT CIRCUIT and Vehicle Diagnostic Tester in the "Guided Fault Finding" function.