2017 Sierra Fans and AC not working

[minkota]

I recently purchased a 2017 Sierra, suddenly the AC stopped blowing cold. I went to check the refrigerant level when I realized the radiator fans are not turning on. I I disconnected the Coolant sensor and the fans will come on as expected. all fuses and relays test good. I replaced the Coolant Sensor just for piece of mind since I just purchased the truck but it made no difference. also the temp on the gauge will not go above 210 even though the fans are not turning on (not sure I believe the gauge). 

If anyone else has had this issue, I could sure use some help on where to check next. Thanks

[richard wysong]

As always check for codes. A good scan tool will tell you if the fans are commanded on or not and will tell you actual coolant temps

Edited January 28, 2025 by richard wysong

[minkota]

2 hours ago, richard wysong said:

As always check for codes. A good scan tool will tell you if the fans are commanded on or not and will tell you actual coolant temps

There is no Check Engine Light and there are no Codes when using a Scan Tool.

[richard wysong]

the fans probably don't kick on til over 230, most of the country is cold right now so sitting idling it may not get hot enough to trigger them on. If your scan tool does live data you can monitor the coolant temp and see when they are commanded on. As far as them not running with the a/c on it could be a bad high pressure switch. Best to follow the trouble tree in the FACTORY service manual

[mikeyk101]

What did you discover when you checked the refrigerant level?

[minkota]

22 hours ago, richard wysong said:

the fans probably don't kick on til over 230, most of the country is cold right now so sitting idling it may not get hot enough to trigger them on. If your scan tool does live data you can monitor the coolant temp and see when they are commanded on. As far as them not running with the a/c on it could be a bad high pressure switch. Best to follow the trouble tree in the FACTORY service manual

77 degrees here in South Florida today, it doesn't take long to reach 230 with no cooling fans. the fans continue to no come on. engine temp reached 245 (per scan tool) when I shut truck off.

[minkota]

17 hours ago, mikeyk101 said:

What did you discover when you checked the refrigerant level?

Compressor will not Engauge while the fans are inoperable so I am unable to get a reading right now. I guess I could force the compressor on, but its not the main concern. i am not sure if the non-working AC is a symptom or the cause.