On this '11 Grand Cherokee the blower motor would cut in and out, seemingly at random but there may have been a pattern.
The interweb suggests this is actually the system signaling a problem with climate control. Why you would choose
this as an indicator and why you'd expect anyone to
know this is what it means is a secret closely held by Chrysler Stellantis Cialis.
Even more curious, my upper-end Otofix found no HVAC codes. Indeed, I could access the HVAC manufacturer side, look at live data like commanded positions and perform live tests like moving actuators with the scanner, but no codes were present in the HVAC module/BCM. Nice work Stellantis Cialis.
However I noticed the right hand temp control did nothing, and so this seemed a good place to start.
I tore into the dash (easy) and found the actuator hanging by its harness, completely disconnected from the duct box. In a case of just-when-you-think-you've-seen-it-all, someone had drilled two holes in the pinion and cobbled it in place with an impressively long coat hanger carefully wedged under the center console. Presumably the two holes were SUMMER and WINTER settings
I can understand such things in the Alaskan Bush or a third world country, but here O'Reilly carries both the actuator and the gear that always breaks (albeit Murray which is
probably Four Seasons?). The blend door itself moved freely by hand with positive stops, so nothing seems broken internal to the box.
The gear was MIA as were the plasti-screws, and the existing actuator (Dorman logo) was dead, not moving even when I applied polarity.
I installed a new gear and actuator and everything works as it should. Fortunately I hoard plasti-screws from other projects.
The trickiest thing about these systems is getting them to "try again" because once it determines there's a problem it won't even try to move the actuator for......a certain amount of time?.....a certain number of start cycles? I don't know. Completely unplugging and re-plugging the actuator seemed to work, and my Otofix had a "reset ECU" for the HVAC section which I
think also helped once.
Finally -- if anyone made it this far -- I was looking at a '14 Ram yesterday also with failed passenger side temp controls. It seems
that actuator is on the FRONT of the HVAC box, sandwiched right against the firewall. Replacement requires complete dash removal. I'm just gonna suggest maybe we're over-engineering things and dual zone climate control isn't really necessary.