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Old 11-12-2013, 08:18 AM
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AC Question

I have a 2014 Summit and have noticed that in the AC mode, if my temp setting is 62 and I raise it to 64 or so, heat start blowing out the vents. It will eventually revert back to cold. This morning when I started the car, it was set on 62 and heat started blowing out the vents. I park in a garage. Its even done this in the summer. What's the deal here, I've never had this happen in any other vehicle I've owned. Is this a common thing?
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Old 11-12-2013, 08:28 AM
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I've noticed some oddities there as well on my Overland. If I'm driving around and set it up to 80 or so (cold out) it will be nice and toasty. Then if I start driving at high speed it will go cold on me and I'll have to raise it a couple of degrees again to get it warm again. The only setting that it stays warm is "high." And it's not that it's just not AS warm when it changed...it goes pretty cold when it does (close to outside temp).
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Old 11-14-2013, 03:33 PM
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Re: AC Question

When you start up the GC, it uses an algorithm from both the internal and external temperature sensors. There is a time delay for the sensors to calibrate after startup (see owners manual, spelled out these), of up to a few minutes. Because the sensors are using the temperatures recorded at the last time you parked/shut off the vehicle, the HVAC systems can seem to do some funny things when you restart it some time later if you have it in Auto mode. The same process is used if you remote start, for AC/summer (over 80 deg F) and Heat/Steering Wheel/Seat Heater/Rear Defroster (under 40 deg F). So if it was under 40 deg F when you parked it and later in the day it is 70 deg F when you start it, the heat functions will all be on. If it was 85 deg F when you parked it and later in the day it is 60 deg F, the AC will be on. This and the full-blast fans speed is why I personally rarely use the Auto mode. It is the same basic system in all 2011 - 2014 models that have the dual/auto controls.
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Old 11-14-2013, 04:02 PM
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Re: AC Question

I appreciate the detailed response, that certainly makes a lot of sense and explains what is going on with the HVAC. I've encountered all of what you just mentioned. I guess the only thing that would still confuse me is why would the heat start blowing from a low AC setting after its raised a couple of degrees. This after the car has been running for an extended period of time. I guess I need to go back an reference the Owners manual, it might answer my own question. Thanks again
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