Component Description

WARNING: This page is about a different car, the 2012 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.

A/T fluid warmer

The A/T fluid warmer (1) is installed on the front part of cylinder block of engine.
When engine is started while engine and A/T are cold, engine coolant temperature rises more quickly than A/T fluid temperature. A/T fluid warmer is provided with two circuits for ATF and engine coolant respectively so that warmed engine coolant warms ATF quickly. This helps shorten A/T warming up time, improving fuel economy.
A cooling effect is obtained when A/T fluid temperature is high.

Fig 1: Identifying A/T Fluid Warmer
Courtesy of NISSAN NORTH AMERICA, INC.

A/T fluid cooler (with bypass valve)

A/T fluid cooler (1) is installed in the front of radiator (2) and condenser (3).
A/T fluid cooler is provided with a bypass valve that controls ATF flow. Bypass valve operates by thermo wax and a return spring. Bypass valve fully opens when A/T fluid temperature is approximately 90°C (194°F) and fully closes when A/T fluid temperature is approximately 100°C (212°F).

Fig 2: Identifying A/T Fluid Cooler, Radiator And Condenser
Courtesy of NISSAN NORTH AMERICA, INC.
When A/T fluid temperature is low, the bypass valve is open. Most of ATF therefore returns to the transmission without flowing into the cooler core that has larger flow resistance.

Fig 3: Bypass Valve A/T Fluid Flow Diagram (High And Low Flow)
Courtesy of NISSAN NORTH AMERICA, INC.
When A/T fluid temperature rises [to approximately 100°C (212°F)], bypass valve closes and allows ATF to flow into cooler core. ATF flowing into cooler core is cooled by air stream caused by vehicle travel and returned to transmission.

Fig 4: Bypass Valve A/T Fluid Flow Diagram
Courtesy of NISSAN NORTH AMERICA, INC.