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I have a 2012 Chevy Equinix. 120k Miles. Bought it new. From early on sometimes when we would turn the A/C on it would not blow cold. But if we would take the temperature control knob and turn it from cold to hot and back to cold fast the air would start cooling. We would only have to do this like once or twice a summer. Fast forward to a few weeks ago and this time when we did our little trick it wouldn’t fix the problem. But if we did our little trick maybe 5 or 6 times in a row it would fix it for a day or so. Then that stopped fixing it. I read someplace to pull the HVAC battery fuse for a minute and then plug it back in. Once the fuse was plugged back in you could hear something happening in the dash. The first time I did this fuse trick, the A/C worked perfect for over 2 weeks. Then the issue has returned. This time pulling the fuse and plugging it back in only fixed it for a few minutes. However when it stops working and I turn the A/C off and then back on 10-20 mins later it will start cooling again or sometimes it will just start cooling again on it’s own if I leave it on with it blowing the hot air. Very frustrating. Here is something else to throw into the mix. When this started happening again a couple weeks ago, I noticed the outside temperature that is displayed on the radio screen was off by 10-15 degrees and then when the A/C would stop cool and blowing hot air, the outside temperature displayed would drop down to the negative number so. Like it was 20 below outside when here in Vegas it was 100°. I’m stumped. Obviously the compressor is working because it worked fine for 2 solid weeks after this issue started happening and with the ambiant air temperature being wrong I’ve got to believe it’s an electronic part going out. Any help or ideas is greatly appreciated!

  • Welcome here. In my own opinion, replacing the outside temperature sensor would be a good move. They're pretty cheap and they eventually wear out due to thermal cycling anyway. An automatic climate controller would logically start blowing hot air when it senses cold outside. Also, carefully clean the sensor's harness connector contacts when you replace it. – Al_ Sep 5 '18 at 9:27
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    @Al_ - I don't really think that's a logical assumption. AFAIK, the outside temp sensor and the internal temp for the HVAC are not tied together, nor logically do they need to be tied together. There should be a separate internal temperature sensor, or possibly two for dual zone automatic control, inside the vehicle. It really shouldn't care what it is outside to maintain the temp inside. Yes, change the outside temp sensor, but I think this is more of a coincidence than anything. – Pᴀᴜʟsᴛᴇʀ2 Sep 5 '18 at 10:30
  • @Pᴀᴜʟsᴛᴇʀ2 You're right, there's also an internal temperature sensor, but logically if the line to the external one is suddenly signaling a very cold temperature the climate control unit could take this into account and keep the interior from becoming cold by beginning to provide hot air instead of cold one (also, too low of an external temperature might also cause the climate control unit to immediately cut the compressor off and this can mean ambient air from the vents too). – Al_ Sep 5 '18 at 10:40
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    @Al_ - That's a real stretch. There's no real reason for the two to be connected. The only concern of an automatic internal control is the temperature of the inside of the vehicle. – Pᴀᴜʟsᴛᴇʀ2 Sep 5 '18 at 11:19
  • @Pᴀᴜʟsᴛᴇʀ2 Trust me, one application of a temperature sensor redundant to the interior air one (the outside temperature sensor) i know about is calculating an optimal cabin temperature setpoint without even asking the driver to input the desired cabin temperature (which can always be overridden by the driver, though), so that you just push a button and wham, you get always comfortable no matter how cold or hot or sunny or cloudy it's outside. It's not so far-fetched as you may think. – Al_ Sep 5 '18 at 15:09

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