2009 Yukon radiator fan

[mikewack]

My 2009 Yukon radiator fan will not come on even when the engine gets hot unless the air conditioner is turned on.

I have replaced the radiator fan module, the high-speed fan module, low speed fan module, and both 40a fuses.

I replaced the temperature sensor that goes on the engine and I put in a brand new radiator fan

When the engine is hot and I turn on the air conditioner both fans come on and cools the engine on the low fan speed

When the engine is hot, I turned the AC off and the fans quit and if it idles long enough, they check engine light comes on until I turn the AC back on and it cools the radiator

Since I owned the car, the fans came on when the car started, and when it got hot or when I turned on the AC, the fans went on high speed.

I don’t think anything is left except for the computer and broke wiring, but I would love some advice

 

[Fless]

Use a good bidirectional scanner on it to see if there are any DTCs, and post them in this thread. The scanner can also command the fans on and off, and tell you if the commanded state is the same as the actual state (on, speed, etc.).

You might want to see if your (new) engine coolant temperature sensor is reporting properly, with the scanner.

What temperature is the thermostat?

 

[swathdiver]

There are three relays for the fans. Sounds like one or two of them are kaput. They are located in the under hood fuse box.

 

[Marky Dissod]

My 2009 Yukon radiator fan will not come on even when the engine gets hot, unless the air conditioner is turned on.
I have replaced the radiator fan module, the high-speed fan module, low speed fan module, and both 40a fuses.
I replaced the temperature sensor that goes on the engine, and I put in a brand new radiator fan.

When the engine is hot and I turn on the air conditioner, both fans come on and cools the engine on the low fan speed.
When the engine is hot, I turned the AC off and the fans quit, and if it idles long enough, the check engine light comes on until I turn the AC back on and it cools the radiator.

Since I owned the car, the fans came on when the car started, and when it got hot or when I turned on the AC, the fans went on high speed.
I don’t think anything is left except for the computer and broke wiring, but I would love some advice

There are three relays for the fans. Sounds like one or two of them are kaput. They are located in the under hood fuse box.

This, exactly, since you covered nearly everything else.
Also, your motor oil ATF and coolant have come awfully close to overheating, past 230F.
No harm done in changing those out at first opportunity.

If you want your fans to turn on sooner and give you a somewhat better margin against overheating, get tuned.
One of the MANY things addressed by a tune is GM's very high fan-on temp thresholds.

 

[Fless]

I have replaced the radiator fan module, the high-speed fan module, low speed fan module, and both 40a fuses.

What are these "fan modules?"

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.