Transmission Cooler: Description and Operation

Transmission Cooling

COMPONENT LOCATION - STANDARD CLIMATE









COMPONENT LOCATION - HOT CLIMATE









OVERVIEW
The AWF21 transmission uses an external fluid cooler to reduce the temperature of the transmission fluid.
In standard climate markets a plate type cooler is used and uses engine coolant to reduce the fluid temperature.
In hot climate markets, an air blast cooler is used in addition to the plate type cooler used on standard climate vehicles. This provides additional cooling for the higher ambient temperatures experienced in these countries.

COOLER - STANDARD CLIMATE









The transmission fluid cooler is attached to the Left Hand (LH) end of the radiator. The fluid cooler is an aluminum housing comprising louvered fins and plates. The plates allow a cross-flow of transmission fluid and engine coolant through the cooler. The plates are immersed in engine coolant from the 'cold' side of the radiator which provides cooling of the transmission fluid by the temperature differential between the transmission fluid and the engine coolant.
The engine cooling system has a low temperature zone in the top third of the radiator. The engine coolant flow through this section of the radiator is restricted by the transmission fluid cooler. Therefore the engine coolant has a slower flow rate across the cooling tubes of this section of the radiator. This cools the engine coolant more than the lower part of the radiator and consequently provides increased cooling of the transmission fluid.
Fluid is supplied from the transmission fluid pump into the lower connection of the cooler. After passing through the cooler, the fluid passes out of the upper connection and is returned to transmission fluid pan.

COOLER - HOT CLIMATE









In hot climate markets, the transmission fluid cooling system uses the same cooler as the standard climate system, but with an additional air blast cooler located in front the radiator and the Air Conditioning (A/C) condenser.
The operation of the fluid cooler is as described for the standard climate cooler. The air blast cooler comprises 2 end tanks, interconnected with hollow plates. The plates allow transmission fluid to flow from one end tank to the other, with the air flowing over the plates cooling the fluid as it passes through the cooler.
The transmission fluid output from the transmission pump is split between the standard climate cooler and the air blast cooler. Some of the transmission fluid from the transmission pump is diverted into the air blast cooler. The fluid flows through plates in the cooler and the air flow over the plates removes the heat from the fluid. The fluid is then directed back to a tee connection with the fluid pipe to the standard climate cooler and is then returned to the transmission.