Here's a weird AC issue

[fasteddy]

15 Escalade. So my front AC won't blow cold unless I turn the rear AC on then its fine. Weird huh? Gotta be a switch or a sensor somewhere but I'm not an AC guy so have no idea. Any thoughts?

 

[Joseph Garcia]

@swathdiver

 

[swathdiver]

15 Escalade. So my front AC won't blow cold unless I turn the rear AC on then its fine. Weird huh? Gotta be a switch or a sensor somewhere but I'm not an AC guy so have no idea. Any thoughts?

When this happened to me on two other cars, it turned out to be a fan relay that needed replacing.

 

[B-train]

Maybe the control from the master isn't actually engaging the A/C. The rear calling for it may take a diffent path, or bypass the bad one? You probably need to replace the A/C control panel - seems common on these. Did it on my 2017 a couple years back already. In the Yukon it comes as one panel with the radio and everything.