Ventilation and blower speed

[HDSlowride]

I have a 2021 JLUR. This is my situation and while it may have been covered in the past, I don't see it right off the bat. In the wintertime, and cool temperatures, when I turn on my heat to say, 72 degrees F (Auto mode) and let's just say that it is 40 degrees outside. In every other vehicle that I've had for the past 20 years, the blower fan speed will automatically be on high until the set temperature is reached. However, on my Rubicon, my fan speed will not increase unless I switch to manual mode and increase it myself.
In the summertime, the blower speed works just as it should in Auto mode, blowing very hard until the set temperature is approached.
What am I missing here? To warm the cabin up in winter, I have to set it on manual to circulate enough air to warm things up quickly when it should do it automatically.

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[HDSlowride]

No one else has experienced this issue?

 

[Dave928]

i think it has to do with which vent setting you're on. don't remember exactly, but it's been posted before.

 

[rcadden]

Could it be that its waiting for the engine to heat up enough to blow hot air? Have you ever left it on auto to see how long it takes to start blowing full, and monitored the engine temp at the same time?

 

[mwilk012]

It does what it wants. If you want it to do what you want, change the setting you want. Turn the temperature up in auto, or change the blower speed. It’s working as intended.

 

[Ratbert]

Could it be that its waiting for the engine to heat up enough to blow hot air? Have you ever left it on auto to see how long it takes to start blowing full, and monitored the engine temp at the same time?

That seems like the most obvious answer. It's not going to blow ice cold air at you until it warms up.

 

[HDSlowride]

Many times during this past winter in cold weather, I would turn on the heat after a few miles, in auto mode. After driving for a while and noticing that it wasn't really warming up in the cabin, and that there was barely any air flow from the vents, I would increase the temperature setting, gradually increasing it to 85. No change at all in the blower speed in auto. I could switch it to manual and increase the blower speed, so I knew that indeed the fan was capable of running at the various speeds. It just will not do it in auto.
So it isn't "working like it's supposed to". The a/c is working just as intended now that it is warm weather. Blower runs at a wide open speed in auto until the cabin temperature comes down and approaches the set point.
I sort of think it has something to do with a cluster of resistance controls in the circuit that I have been able to spot briefly while doing some google research. Just haven't pinpointed it yet.
Thanks for your helpful and thoughtful insight.

 

[AFD]

Mine does this too iirc, and I just figured it was waiting to blow more air until after it was heated up a bit more. When it's really cold, I'll just leave it on auto and crank the temp up to near max (usually 81F or so) and it seems to turn the blower on a little sooner and warm up the cabin quicker.

Like @mwilk012 said, the JL HVAC system just tends to do what it wants in auto. Unfortunately, adjusting all of the various controls manually is a bit dangerous to do while driving imo. Other than the middle blower dial, it's just f'ing identical buttons everywhere and nothing like old-school knobs and sliders where you could control everything without taking your eyes off the road. Absolutely one of the most poorly thought out and unintuitive HVAC control designs I've ever seen in all my years of driving different vehicles.

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