16 Tahoe electric fans and AC issues

[Wicked Mayhem]

2016 Tahoe, electric fans barely running with the AC on. I can disconnect the coolant temp sensor and the fans run full speed and the AC starts to blow cold. But when I hook it back up the fans barely turn and the pressures on the AC go up and blows warm. Any ideas?

 

[Geotrash]

2016 Tahoe, electric fans barely running with the AC on. I can disconnect the coolant temp sensor and the fans run full speed and the AC starts to blow cold. But when I hook it back up the fans barely turn and the pressures on the AC go up and blows warm. Any ideas?

You need a good bidirectional scanner to see the commanded vs actual on the fans to diagnose this. But at least you know the fans are capable of full duty cycle operation. The usual suspect here is the coolant temp sensor. Even if it seems to be displaying the correct temperature, it may be off by enough to throw off the fan operation. It could also be a bad fan relay. You may try swapping relays around to see if it changes anything.

 

[Wicked Mayhem]

You need a good bidirectional scanner to see the commanded vs actual on the fans to diagnose this. But at least you know the fans are capable of full duty cycle operation. The usual suspect here is the coolant temp sensor. Even if it seems to be displaying the correct temperature, it may be off by enough to throw off the fan operation. It could also be a bad fan relay. You may try swapping relays around to see if it changes anything.

I finally had a chance to compare her AC next to my truck(18 Silverado). Both vehicles sat overnight. Turned both on with max ac, full fan speed etc everything the same. Her electric fans were not running and blowing out basically hot air(texas) turned mine on, electric fans running at I’d say 30% or so?? And AC blowing out ice cold nearly instantly. I swapped her electric fan relays with two other 40amps, with no change. I have replaced her coolant temp sensor with a OEM sensor in the past but I guess that will be my next thing to try as it’s really easy to change. Is there an actual fan controller on these things?