I have a 2010 lnf that the cooling fans will not come on unless the AC is on
i have switched out the 3 relays associated with the lnf fans with no change checked wiring and nothing even the temp sensor seems to be good. If I let it sit while running within about 5 mins it's 215+ degrees. If I switch on the AC or just start moving with 30 seconds to 1 minute it's back around normal at 189.
I know that the AC switch is a completely different circuit than the switch that tells it to start coming on at 199 but I don't know much more than that there just doesn't seem to be a lot of info out there on the lnf fan setup
If anyone has some recommendations on where to go from here that would be much appreciated thanks

 

This is the most complete set of info I could find on lnf cooling fans
My question from this info is what and where is the cooling fan control module and can it be tested
For the LNF:

Cooling Fan Description and Operation

Cooling Fan Control 2.0L

The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the PWM signal. The cooling fan speed can be adjusted from 10 percent to 94 percent duty cycle. 94 percent is considered high speed fan.

The ECM commands fans ON under the following conditions:

Fan Control During Engine Operation (Engine ON)
• Fixed 94 percent duty cycle commanded when the following conditions are met:

- Engine oil temperature is greater than 140°C (284°F).

- AT transmission temperature is greater than 140°C (284°F).

- Intake air temperature is greater than 65°C (149°F).

- Engine coolant temperature sensor faults have been detected (electrical or rational).

• Variable duty cycle from 15-95 percent is commanded when:

- From all available requests, the maximum requested duty cycle is selected and commanded.

- Dependant on engine coolant temperature, 0 percent up to 92.9°C (199.22°F). Then 15 percent at 93°C (199.4°F) to greater than 94 percent by 121°C (249.8°F).

- Dependant on A/C pressure sensor, 0 percent up to 10,979 hPa. Then 15 percent at 10,980 hPa to greater than 94 percent by 23,529 hPa.

- Fans commanded off during running operation when the above conditions are not met.

Fan Control During After-run (Engine OFF)
• Fixed 36 percent duty cycle commanded after shut-down when the engine coolant temperature at shut-down is greater 101°C (213°F).

• Fixed 60 percent duty cycle commanded after shut-down when the engine coolant temperature at shut-down is greater than 108°C (226.4°F).

• Fans commanded OFF during after-run when:

- System voltage is less than 11.5 V.

- After-run time is greater than 420 seconds.

- Coolant temperature drops below a variable threshold

 

there isn't a cooling fan module, ecm drives the fans based on temp sensors and ac request. The ac being on doesn't start the fans due to temp but due to the high side pressure sensor.

Cooling Fan Control
The engine cooling fan system consists of one cooling fan and two relays. The cooling fan has 2 windings in the motor, one winding is for low speed and the other winding is for high speed. Voltage is supplied to the relays from the 30 A cooling fan 1 and 30 A cooling fan 2 fuses. The engine control module (ECM) controls the low speed fan operation by grounding the cool fan 1 relay control circuit. When the cooling fan 1 relay is energized, voltage is delivered to the cooling fan low speed winding. The ECM controls the high speed fan operation by grounding the cool fan 2 relay control circuit. When the cooling fan 2 relay is energized, voltage is delivered to the cooling fan high speed winding. The cooling fan motor is grounded through its own ground circuit.

The PCM commands Low Speed Fans ON under the following conditions:

•Engine coolant temperature (ECT) exceeds approximately 106°C (223°F).
•A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
•After the vehicle is shut off, the ECT at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans ON under the following conditions:

•ECT reaches 110°C (230°F).
•A/C refrigerant pressure exceeds 1 655 kPa (240 psi).
•When certain DTCs set

Cooling Description and Operation 2.0L (LNF)
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood junction block.

During low speed operation, the ECM supplies the ground path for the low speed fan relay, which is cool/fan 1, through the low speed cooling fan relay control circuit. This energizes the cool/fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool/fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cool/fan ser/par relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the ECM supplies the ground path for the cool/fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the ECM supplies a ground path for the cool/fan 2 relay, which is the high speed relay, and the cool/fan ser/par relay through the high speed cooling fan relay control circuit. This energizes the cool/fan ser/par relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cool/fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool/fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.

When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.

Anyway here is the fan diagram for you,

 

Thank you
that gives me some things to look at

 

Bump for morning views

 

According to what Kolt said your fans aren't set to come on until your ECT reaches 223F. If that is the case then your fans could be working properly. Your ECT just isn't high enough for them to turn on.

 

215 isnt enough to turn on the fans. Seems like its working normally.

 

Since the PCM commands the fans to turn on in all cases (rather than having separate switches for A/C and coolant temps like old skool styles) I think the fact that the fans come on when the A/C is on is a good sign it's working. Otherwise there'd be an issue with the ECT sensor (since the relays are working).

 

The pcm commands the fans by different inputs, so you can have high speed but no low speed due to how the circuits are routed with the relays. Need to check that your left low speed kicks in when it reaches temp with ac off. Now 223 is a approximate temp so it should kick in anywhere between 215 and 229 but not exceed 230. If it does and your high side kicks in then you have a low speed problem.

 

Okay I will let it get hotter and see if the high-speed fans come on it appears to me that does the high and low speed fans are working with the AC

Now I have found contradicting information in this thread and others. In my second post is what i found in another thread that says it's for the LNF not lsj
If I'm reading it correctly it says the low speed fans should come on at 199 degrees and the high-speed fans at 230. Nearly every thread that you read on this site about Cooling says that the fans should come on at 223 degrees and this is where I'm getting confused
​​I've I've had my car 7 years now in Texas that thing has never been over 207 degrees in any situation and if I let it sit and run for more than 5 minutes It'll be well over that with no fans running

 

What I got is straight from gm service information, I can check and see when I get home what temp each fan kicks in at.

 

@Kolt , hey bro. I’m trying to sort out a cooling fan problem. 09 LNF fan 1 is not coming on at all. I have it set to 95% @ 194. Comes on and goes off as it should. I checked all 3 relays and the fuses. All seem good. I replaced the fan since I get 13.7v at the connector to fan. Still nothing. I am going to order new relays just to be certain, but I’m at a loss here. Hoping you might have some insight.