Cooling fan not functioning

A pontiac montana ? There are three relay's that control your cooling fans ! unplug what sensor ? The engine coolant temp. sensor is an input to the PCM - engine computer . When temp. reaches 213 degrees the PCM energizes the relays , depending on low or high speed . Using a scan tool to see if the PCM will turn on the fans an checking engine coolant temp.data is the right way to diagnose this . Relay Driven Dual Cooling Fan Diagnostics

The PCM regulates voltage to the coolant fan relays, which operate the fans. Refer to Engine Controls.

Engine Cooling Fan Description - Electric
The electric cooling fans are used to lower the temperature of the engine coolant flowing through the radiator. They are also used to cool the refrigerant (R-134a) flowing through the A/C condenser.
Operation
The electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the PCM. The cooling fan has one speed. The PCM turns the cooling fan ON by grounding the coil of the cooling fan relay when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.
Power for the cooling fan motors are supplied through Cool Fan #1 and Cool Fan #2 relays. The cooling fan relays are energized when current flows from the fuses in the Cell 23: Cooling Fan Controls , and through the relay coils to ground through the PCM. The Low Speed fans control circuit is grounded for low speed fans operation. During low speed fans operation, both fans run at a slow speed. The High Speed fans control circuit is grounded for high speed operation. During high speed fans operation, both fans run at high speed.
Important: When certain Diagnostic Trouble Codes (DTCs) are present, the PCM may command the cooling fans to run all the time. It is important to perform Powertrain On Board Diagnostic (OBD) System Check prior to diagnosing the engine cooling fans.
If a problem that involves the low speed cooling fan relay control circuit exists, DTC P0480 should set. If the problem affects the high speed cooling fan relay control circuit, DTC P0481 should set. A problem with the ECT sensor should set DTC P0117, P0118, P1114, or P1115. Any of these DTCs will affect cooling fan operation and should be diagnosed before using the Cooling Fan Diagnosis tables. The Cooling Fan Diagnosis tables should be used to diagnose the PCM controlled cooling fans only, if a DTC has not set.

The engine coolant temperature (ECT) sensor (3) is a thermistor, a resistor which changes value based on temperature, mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40°C) (-40°F), while high temperature causes low resistance (70 ohms at 130°C) (266°F).
The PCM supplies a 5 volt signal to the ECT sensor through a resistor in the PCM and monitors the terminal voltage. Since this forms a series circuit to ground through the ECT sensor, high sensor resistance (low temperature) will result in high PCM terminal voltage. When the resistance of the ECT sensor is low (high temperature), the terminal voltage will be drawn lower. This terminal voltage indicates engine coolant temperature to the PCM.
A hard fault in the ECT sensor circuit should set either a DTC P0117 or P0118. Remember, these DTCs indicate a malfunction in the engine coolant temperature circuit, so proper use of the DTC table may lead to either repairing a wiring problem or replacing the sensor, to properly repair a problem.

The engine coolant sensor is an input to the PCM , Two wire's both go to the PCM .An the PCM turns on the cooling fans !

DTC P0480 Cooling Fan Relay 1 Control Circuit
DTC P0481Cooling Fan Relay 2 Control Circuit
The Body Control Module (BCM) request the cooling fans. The BCM sends a Class 2 message to the PCM in order to enable the fans based on various inputs. Thebattery voltage travels to all three cooling fan relay coils. The PCM enables cooling fan relay #1 by providing the ground path. The PCM enables cooling fan relays #2 and mode control together by providing a ground path. The left and right cooling fans are connected in series. This will enable both fans on low speed when the fan #1 relay is energized. When all three fan relays are energized, both fans will operate at high speed. The high speed is possible because the fan relays are wired in a parallel circuit. When the PCM detects that certain DTCs are set, the PCM will enable the cooling fans.
The PCM will enable the engine cooling fans when certain Diagnostic Trouble Codes are set.

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.
1
Did you perform the Instrument Cluster System Check?
--
Go to Step 2
Go to Instrument Cluster System Check
2
Turn the ignition switch to the ON position.
With the scan tool select Instrument Panel Cluster, Special Functions, Instrument Panel Cluster (IPC) gauges.
Perform the Coolant Gauge Sweep Test.
Does the coolant temperature gauge complete a full sweep when commanded?
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Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls
Go to Step 3
3
Replace the instrument cluster. Refer to Instrument Cluster Replacement .
Did you complete the repair?
--
Go to Instrument Cluster System Check
--

Your best bet would be to take your vehicle to a qualified repair shop that knows how the system works . An has the tools to diagnose the problem .

Deanna, check to see if your A/C is in the on position, this could cause fan to run a lot. If this is not the case, take truck in for diagnoses at a good shop, could be a faulty heat/fan sensor or sticking relay. Check the attached links,instruction and guides, Good luck
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Diagnose Engine Cooling Fan Relay Problem
2007 Chevy Silverado Fans Always Run Engine Cooling Problem 2007
cooling fan running all the time

You still have many other components in that system that has to be in working order for the cooling fan to work properly. The cooling fan is turned on when engine temp reaches a predetermined temp, usually around 220-230 degrees F. the ECT (engine coolant temp) sensor siganls the ECM (Engine Control Module) to ground the cooling fan relay or cooling fan module(if equipped) and if the cooling fan fuse is good and the fan has power to it the realy will complete the ground for the fan to run. You may need to have a qualified technician diagnose the problem if the obvious things like fuses and good grounds are not the problem.

Hope this helps.

The inoperative cooling fan needs to be diagnosed,run the engine until it reaches 229degrees and seeif the fan gets power to turn on if so then replace the fan if not check the wiring and cooling fan relay and repair or replace as needed.

boost vehicle but before you do that remove the fuse for the cooling fan till you get it to turn over once its running plug said fuse back in and get it to a shop to have them diagnose why the fan is on to long

No,you need to change the cooling fan relay,it is stuck.

Fifteen minutes! you have bigger problems than only the fans the fans are controlled by a thermo switch that is heated by the coolant, If you have no coolant the sensor cannot activate But fifteen minutes seems like you may have a headgasket problem and steam cannot heat the coolant sensor.OperationNotesThe electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the Powertrain Control Module (PCM) . The PCM turns the cooling fan ON by grounding the coil of the cooling fan relays when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.

Power for the cooling fan motors are supplied through Maxifuses(R). The cooling fan relays are energized when current flows from the fuses in the Underhood Accessory Wiring Junction Block, and through the relay coils to ground through the PCM. The Coolant Fan 1 Relay Control Circuit is grounded for low speed fans operation. During low speed fans operation, both fans run at a slow speed. The Coolant Fan 1 Relay Control Circuit is grounded for high speed operation. During high speed fans operation, both fans run at high speed.

IMPORTANT: When certain Diagnostic Trouble Codes (DTCs) are present, the PCM may command the cooling fans to run all the time. Perform the A Powertrain On Board Diagnostic (OBD) System Check prior to diagnosing the engine cooling fans.

For more information regarding the Charging System, refer to Charging System Description , and Charging System Circuit Description in Starting and Charging.

If a problem that involves the low speed cooling fan relay control circuit exists, DTC P0480 Cooling Fan Relay 1 Control Circuit should set. If the problem affects the high speed cooling fan relay control circuit, DTC P0481 Cooling Fan Relay 2 Control Circuit should set. A problem with the ECT sensor should set DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage, DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage, DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage, DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage. Any of these DTCs will affect cooling fan operation and should be diagnosed before using the Electric Cooling Fan Diagnosis.

For more information regarding the Cooling System refer to Engine Cooling Fan Description - Electric, and Cooling System Description in Cooling System.


Here is the electrical schematic and how it all is suppose to work,
If you need any further help please contact me Thank you,Randy If you find this information helpful please give me a good rating

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The fans only run when the engine reaches approxminatly 235 degrees F. on the guage that is near the end of scale just before guage show "HOT" I don't think you have a problem, allot of folks out there don't know about this.