I believe it is, and if it isn’t, then there is two different issues going on between the two systems. If we want to figure this out, then we need hard data from the HVAC module, not a bunch of “I live here in this climate, and mine is or isn’t fine”, because everyone “feels” temperature differently. 70* to me is like hell, where 70* to my wife is like an icebox.
The single zone MTC just uses a blower motor with different speeds, two blend doors, and the evaporator with it’s temp sensor. If you’re set all the way on cold, then the blend door should be shut and sealed, and the air coming off the evaporator should never see the heater core. So, with the single zone, if you’re set all the way cold, the HVAC module is reporting 36* from the evaporator, and you’re shooting 50* with a temp gun at the vents, then you have a blend door sealing issue.
With the dual zone ATC system, now you have the outside air temp, the cabin temp sensor, a different sun sensor, and four in duct temp sensors that all come into play on how the HVAC module controls the climate.
@g00fy has pulled some data logs, and it seems there’s a few weird readings going on. The cabin temp sensor seems to be reporting the temp that the climate controls are set at, not the temp of the air around it. This alone would explain the majority of the issue.
All we need is for a few more people with dual zone ATC that have AlfaOBD to data log some temps. Mainly the cabin temp vs the climate temp setting, and how it reacts when 1) the climate setting temp is changed, and 2) when the air temp around the cabin temp sensor is changed with a hair dryer. Then we can start picking up a pattern. But, every time
@g00fy suggests this, it always gets sidetracked to “adding a valve to bypass the heater core”, which is not a solution. If everyone does this, then nobody at FCA will know there’s an actual HVAC programming issue. If we get enough hard data on the temp sensors, then “someone” with FCA can be alerted- “hey, these temps sensors are giving bad info”, and that’s the only way TSBs get put out for software updates.