Originally Posted by jdg857

I was on the road today so I did set the front to cool (72 degrees F) and the rear to warm (84 degrees F) with the rear air outlets switched to warm air, and while it was warmer out of the rear seat outlets it wasn't hot, but the ambient air was around 86 degrees F, so there may not have been a need for much heat. I then turned the front units up to 84 and the rear air was warmer. When I put the front down to 60, the rear units stayed warmer than before. I don't know if this helps, but it seems the rear air conditioning units are somewhat dependent on the front air temperature settings. It took several minutes after each change for the air temperature to stabilize.

I adjusted the fan speed on the rear unit and it had no effect on the front fan speed, so you may have an issue there.