Catera V6-3.0L VIN R (1997)
Radiator Cooling Fan Motor: Description and Operation
Auxiliary
DESCRIPTION
If the temperature reaches 105°C (221°F), the secondary cooling fan temperature switch contacts will close enabling the fan control relays K52
and K28 to energize. When the fan control relay K52 energizes, the auxiliary engine coolant fan #1 will go to full speed because it is no longer in
series with the auxiliary engine coolant fan #2. When the fan control relay K28 is energized, Be from fuse #40 will allow the auxiliary engine
coolant fan d2 to go to toll speed. With the stage 1 contacts of the primary cooling fan temperature switch closed, the ECM cooling blower, the
timing control pump, and the engine coolant fan will continue to operate.
OPERATION
The secondary cooling fan temperature switch contacts will open when the coolant temperature reaches 100°C (212°F). This will cause the
operation of the auxiliary engine coolant fans (#1 and #2) to operate differently as the primary cooling fan temperature switch designates. If the
coolant temperature reaches 110 (230°F), the secondary cooling fan temperature switch stage 2 will close enabling the fan control relay K67 to
energize. When the fan control relay K67 energizes, B+ from fuse #42 will be applied to the engine coolant fan directly. This will cause the engine
coolant fan to operate at full speed. All the other operations that were taking place before the coolant temperature reached 110°C (230°F) will
remain in effect. The primary cooling fan temperature switch stage 2 contacts will open when the coolant temperature reaches 105°C (221°F) and
the engine coolant fan will return to half speed. At coolant temperatures above approximately 110°C (230°F), all three coolant fans are operating
at full speed. The ECM cooling blower, the timing control pump, and the auxiliary water pump are also operating. Only six of the seven relays
operate at this time, unless the air conditioning system is turned ON. In this case, the fan control relay K87 and the A/C compressor relay K60 will
also operate. To prevent inadmissible high refrigerant pressure in the refrigerant circuit, the auxiliary engine coolant fans (#1 and #2) are switched
from the first speed to the second speed at refrigerant pressures above approximately 1,900 kPa (275 PSI). When the pressure drops below
approximately 1,500 kPa (217 PSI), the auxiliary engine coolant fans (#-I and #2) are switched back to the first speed.