Front Defrost NOT turning on AC Compressor?

[alrashid2]

Hey guys, I'm baffled here. These Rangers are the first vehicles I've had with such strange, fancy HVAC systems.

This morning was the first morning I ever needed the front windshield to be defogged. Go into the Vent setting and turn on Front Defrost vent location. Drive for a few minutes, and nothing is happening... Air is blowing out at windshield, but still foggy. I notice that the air coming out of the vents also hasn't changed temperature and feels ambient.

I then click on the AC button and lo and behold, the front windshield starts to defog!

Get to work and park the truck. Do some back and forth between the HVAC screen and looking under the hood:

* Defrost vent location off, AC off: AC compressor off

* Deforst vent location ON, AC button not manually turned on: AC compressor still off...

* Defrost vent location ON, manually turned on AC button: AC compressor kicks on!

I'm so confused here... shouldn't I just be able to turn on the Defrost vent location and it, you know, defrost? I highly doubt that vent location is just meant to blow air at the windshield without defrosting right? I also tried the Max Front Defrost button which seemed to work, but I hate that it blasts Max Heat so I don't plan on using that.

Could someone do me a favor and check their truck? With the AC otherwise off, when you turn on the Front Windshield vent location like in my photo below, does your AC compressor automatically kick on?

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[alrashid2]

Well, got an update...

Played around a bit after work. I explain this video I recorded, but what I realize is is that most vehicles, when in Defrost mode, automatically turn off the Recirculate Air mode in a car, and don't allow you to turn it back on.

Well, when I have the Defrost Vent Location on and the Front Vents and/or Footwell Vents, Recirculate doesn't automatically turn off and I can turn it off/on myself.

When I have only the Defrost Vent Location turned on, the Recirculate automatically turns off and is locked out from being turned back on. Also, when doing this, the AC compressor kicks on and cold air starts coming out.

Really odd design choice. So, if you turn on Defrost vent location with the Front and/or Footwell location(s), it just blows air at the windshield and doesn't defrost... what's the point of that?

 

[alrashid2]

Well, dropped off my truck for an unrelated issue (cam phaser replacement if you've been following my other thread) and got a Bronco Sport Outer Banks as a loaner vehicle.

Did the same HVAC test, and it behaves exactly the same. So I guess Ford's just act like this lol. Very odd, and even odder that I can't find anyone online discussing this? Seems so odd. I've never seen a vehicle that doesn't turn on the AC compressor when Front Windshield Defrost is selected with a second vent location.

Hopefully this helps out someone else who inevitably googles it!

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