Mechanics

RADIATOR

2000 Cadillac Catera

Engine Cooling problem
2000 Cadillac Catera Front Wheel Drive Automatic

This cadillac catera is a 3.0 ltr.

There are 2 switches on this radiator and we need to know which one makes the fan turn on and off. At this point the fan does not run.
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Tbail1
April 16, 2009.



The correct answer is both. You should have three cooling fans on this vehicle, does neither of the three function? I will provide you with some information on this system, the schematic is rather complex.

Engine Cooling Fan Description - Electric
Primary Cooling Fan

The cooling fan switches (7 and 6) and the A/C compressor relay (instead of the ECM) control the relays which power the primary fan (5) and two secondary fans. The primary fan is a " puller" type; the secondary fans are " pusher" type.

The following table explains the temperatures at which the engine cooling fans are energized or de-energized: Engine Cooling Fan Operation Parameters Temperature
Description

Energized

100 °C (212 °F)
The primary fan is energized at low speed using a resistor; the secondary fans are energized in a series (half speed).

105 °C (221 °F)
The primary fan is still energized at low speed; the secondary fans are switched to full speed.

110 °C (230 °F)
The primary and secondary fans are at full speed.

De-energized

105 °C (221 °F)
The primary fan is switched to low speed; the secondary fans are still at full speed.

100 °C (212 °F)
The secondary fans are switched to a series (half speed); the primary fan is still at low speed.

95 °C (203 °F)
All fans are turned off.

The secondary fans are energized in a series (half speed) during A/C operation. This could be stepped up to full speed, or the primary fan could be energized as well, depending on the coolant temperature.

And the description of cooling fans circuit: Cooling System Description
Coolant Fan Circuit Operation
The engine cooling system consists of the following components: • Electric cooling fan

• Auxiliary engine coolant fan #1

• Auxiliary engine coolant fan #2

• Primary cooling fan temperature switch

• Secondary cooling fan temperature switch

• A/C compressor refrigerant pressure switch

• Heater water auxiliary pump

• Auxiliary water pump

• Engine coolant fan resistor

• Six fan control relays

Auxiliary Fans Low Speed, Electric Cooling Fan Low Speed
B+ is supplied to the heater water auxiliary pump whenever the ignition switch is in the ON position. When the engine temperature reaches 100 °C (212 °F), the primary cooling fan temperature switch stage 1 will close, enabling the fan control relay K26 to energize. When the fan control relay K26 energizes, B+ from fuse #52 is applied to the auxiliary coolant fan #1 (auxiliary engine coolant fan #1 is wired in series with auxiliary engine fan #2, through the normally closed contacts of the fan control relay K52). This will cause the auxiliary coolant fans #1 and #2 to operate at low speed. The fan control relay K26 will also supply B+ to the engine coolant fan resistor, voltage passes through the resistor to the electric coolant fan. The engine coolant fan resistor will cause the engine coolant fan to operate at low speed. The primary cooling fan temperature switch stage 1 contacts will open when the coolant temperature reaches 95 °C (203 °F). This will turn all three fans OFF, unless the air conditioning system is ON.

Auxiliary Fans High Speed
When the engine temperature reaches 105 °C (221 °F), the secondary cooling fan temperature switch contacts will close and energize the fan control relays K52 and K28. When the fan control relay K52 energizes, it will ground terminal B of auxiliary engine coolant fan #1. Terminal A of the auxiliary engine fan #1 still receives B+ from fan control relay K26. The auxiliary coolant fan #1 is no longer in series with the auxiliary engine coolant fan #2 and will now operate at full speed. When the fan control relay K28 is energized, B+ from fuse #40 will be applied to terminal A of the auxiliary engine coolant fan #2. The auxiliary coolant fan #2 is no longer in series with the auxiliary engine coolant fan #1 and operates at full speed. Terminal B of the auxiliary coolant fan #2 is permanently grounded to G103. With the stage 1 contacts of the primary cooling fan temperature switch closed, the electric cooling fan will continue to operate. The secondary cooling fan temperature switch contacts will open when the coolant temperature reaches 100 °C (212 °F). This will cause the auxiliary engine coolant fans #1 and #2 to operate at low speed.

Electric Coolant Fan High Speed
When the engine coolant temperature reaches 110 ° (230 °F), the primary cooling fan temperature switch stage 2 will close energizing the fan control relay K67. When the fan control relay K67 energizes, B+ from fuse #42 will be applied directly to terminal A of the engine coolant fan (bypassing the engine coolant fan resistor ) and the engine coolant fan will 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 primary engine coolant fan will shut off.

At coolant temperatures above approximately 110 °C (230 °F), all three coolant fans are operating at full speed. Only five of the six 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.

Engine Cooling Fans (A/C Operation)
When the A/C compressor is turned on, fan control relay K87 is energized and the auxiliary engine coolant fans #1 and #2 will operate in low speed. In order to prevent inadmissible high refrigerant pressure in the refrigerant circuit, the auxiliary engine coolant fans #1 and #2 are switched from the low speed to the high 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 #1 and #2 are switched back to the low speed.

Water Auxiliary Pump
When the ignition is in the OFF position and the engine coolant temperature reaches 100 °C (212 °F), the primary cooling fan temperature switch stage 1 will close, enabling the fan control relay K26 to energize. When the fan control relay K26 energizes, B+ from fuse #52 is applied through the normally closed auxiliary water pump relay K22, allowing the water auxiliary pump to operate. The fan control relay K26 will also supply B+ to the engine coolant resistor, allowing voltage to pass through the resistor to the electric cooling fan. The engine cooling fan resistor will cause the engine cooling fan to operate at low speed. When the engine coolant temperature reaches 95 °C (203 °F), the primary cooling fan temperature switch stage 1 will open, de-energizing fan control relay K26. This will turn the water auxiliary pump and engine cooling fan OFF.

Factoryjack
Apr 16, 2009.