Rear A/C unit control, potential malfunction

[StormTrooperExplorer]

I've noticed the rear A/C control unit in my 2017 Limited is working kind of weird as in it won't work until the engine reaches higher RPMs than idle. When we all get in my car, I turn it on, and a person gets in the rear and turns on the system either by turning up the fan or hitting the center air button it is not turning on. The center button light does not turn on and the fan control is unresponsive. I can manually turn on the rear A/C through the front system, but the rear control unit does nothing. Now, only after I rev the engine or put it in drive and drive off, do the rear controls "turn on" and allow the fan to turn up/down and to adjust the temperature. The rear control unit does have power from start as far as I can tell. It lights up, the rear seat warmers always work no matter what. It's just the fan dial, air direction buttons, and temp dial do not respond.

I rarely drive with anyone in my rear seats, so this is the first time I've noticed this in the 5 years I have had the car. Is this normal operation or is something going on? Can someone tell me if their rear A/C system is responsive right away after turning on the car? Thanks

 

[Digitalgp]

Something sounds off with that. FWIW all I know is on my '15 you have to turn on the rear controls from the main control head in the front otherwise they won't work. You can either control from the front only or the rear only, but not both. Kind of annoying, I liked the control setup far better in my '07

 

[StormTrooperExplorer]

Just an update for future readers: It was the battery. Issue has been resolved.

Over Labor Day weekend, my explorer had a complete battery drain because I left the tailgate open less than 10 minutes to load my kayak after a day trip. This was after starting it and moving it over to near the boat dock to do a quick load and go. After loading I started the car and there wasn't enough in the battery to turn over the engine. I had been noticing some issues with the clock getting reset, but it was very intermittent.

I think when I rev'ed the engine before, it was sending more power to the battery through the alternator, causing the rear system to finally get power/engage.

I replaced the battery last night and the rear system turns on now at start. I think the voltage was getting low enough to not be able to send enough power to the rear A/C system.

 

[peterk9]

A bad or low battery can cause many interesting issues with these vehicles.

Peter