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As best I can tell, they share the same DC-DC converter. Nothing in their workshop manual seems to make a differentiation between the hybrid and Energi models when it comes to DC-DC converter/12v charging systems. Both are still rated for 'up to' 145 amps.

I'd get codes pulled to start with to see if anything is being produced to narrow down the issue. The HVAC system on this vehicle is fairly intelligent and monitors a number of data points that it could show if something is not behaving within normal parameters. Personal preference is using Forscan with a decent OBD2 adapter. For AC/climate related stuff, a cheap Amazon/fleabay Bluetooth adapter will be sufficient. But this combination will also show Ford specific codes that generic code scanners may not. The condenser/engine bay cooling fan should always be running to some degree with the AC compressor running since airflow is constantly needed over the condensor for it to operate correctly. That said, both the cooling fan and compressor are variable speed on the C-Max depending on AC or engine cooling load. For example if it isn't terribly hot or humid outside and the cabin temp has been reached and is just being maintained, they'll slow down quite a bit but should still be audible.

Just as an FYI, Syn3Updater just pulls down updates from Ford's own servers. It's all still official Ford files, just another way to update Sync with some side benefits as a result (including updating to Sync 3.4 which Ford officially doesn't support on our vehicles but works just fine).

Nope. Sync 3 is loaded directly onto the internal storage via USB. No more SD card. In fact no more SD card slot or A/V inputs. Just a couple USB ports. Also the maps for Sync 3 via official methods are VIN locked and you specifically need to provide that when ordering to get the proper USB key. That said, pro tip: Cyanlabs Syn3Updater can load on the newer maps for free at least with the current NA versions... (My 2013 Sync 3 retrofit I've kept up to date this way and haven't paid a single cent). The process is a bit involved for some.

Doing some research on other topics and came across this thread in the Forscan forums: BECM Configuration - FORScan forum The short summary being that they are discussing modifying the battery age counter for the HVB to try and affect the reported battery capacity. As backstory: It has already been sufficiently documented that this is also a thing on the first gen (2010-2012) Fusion Hybrid's with the NiMH based packs and has actually worked for them. In this case the assumption is Ford, under an abundance of caution, put some artificial age based limits in their programming and a lot of those vehicles still had good batteries that were otherwise hampered purely in software after reaching a certain age. Now that's for NiMH chemistry packs which are a COMPLETELY different beast from our current Li-ion based batteries. As a result, I am personally hesitant to put any belief in this really doing anything meaningful given we don't really have to worry about things like the memory effect or regular reconditioning by the BECM to help with said memory effect. But I found the thread intriguing and figured I'd share. I'm interested as a 2013 Energi owner with about 3.7-3.9kwh left in my HVB but I'm very hesitant to mess with this so I'll just leave this here for others to potentially guinea pig if they're adventurous enough. ?

Another reason for charging off-peak other than cost is charging when it is cooler out especially in warmer climates. My electric provider doesn't do TOU rates. Just one flat rate 24/7. I still schedule mine to charge after midnight to help with temps. Just an FYI.

Here are a couple PDFs from the workshop manual detailing where the ambient temp sensor is wired as well as the brief wiring diagram for it. 2013_cmax_ext_mirror.pdf 2013_cmax_front_door_trim.pdf

I can pull up the workshop manual and post full PDFs/pictures tomorrow, but the ambient temp sensor goes through one connector with the rest of the mirror/housing wiring and that sits on the inside of the door up near the mirror itself. I would definitely pull codes (again, with the proper tools. This will be stuff that is on the MS-CAN bus which most generic scantools won't know anything about) if you can as it could also help a little bit in pinpointing the problem or at least confirming if something has or is failing. I'd give about a 90% guess this ambient temp sensor could be the main or at least majority of your problem. The automatic climate control system on these vehicles heavily relies on the ambient temp sensor during normal operation to determine how to operate the heat/AC. Unfortunately AFAIK there's no way to straight up bypass it and make it fully manual. One thing you can try as a workaround/test, though I can't guarantee if it will bypass the ambient temp checks completely, is using Max AC or turning the temp all the way to LO. I -THINK- it's been mentioned maybe a few times by other owners with faulty temp sensors that this works in the short term but my memory is a bit fuzzy on that.

Citation needed. Do you have any further info or leads on where this is from or documented? So far this has been undocumented anywhere in the community.

How's the outside air temp reading from the vehicle itself? This can impact HVAC operation if it is flaking out and it'll be really obvious if it is as the displayed ext temp will fluctuate quite a bit. The exterior temp sensor is in the passenger side mirror and is the little nub that sticks out the bottom. If it is faulty, only replacement is replacing the entire mirror housing. It can in some cases be temporarily messed up by water/moisture making its way up inside the housing due to a car wash or such. Blasting some compressed air up into the housing around the sensor -may- help these cases. Another thing would be to check for any stored codes with a competent code scanner (Forscan with a good MS-CAN capable OBD tool like the OBDLink EX is my preferred go-to). The HVAC system is just as intelligent as the rest of the car and monitors various stats/pressures that -could- pinpoint a cause if there are any related codes stored. This is not guaranteed though. What are the weather conditions when this happens? Does it ever seem to happen more often during hotter and more humid weather? There's another well known condition where the evap core in the cabin will freeze over due to a faulty evap temp sensor. Usually this happens when it is very hot and humid out. It will more cause the airflow to slow and not cool -as well- as normal, doesn't outright switch to warm/hot output, and usually requires manual intervention and will not clear up on its own. This I doubt is what you are running into but figured I'd rule it out here. Those are the immediate things I can think of to check on.

Depends entirely on the warranty and whether you have a CARB length hybrid warranty or not. Baseline is 8 years/100k miles, whichever comes first. So on the age alone you wouldn't be covered. CARB states have a 10 year/150k mile warranty so you are still technically in the 10-year period IF covered under this. Since this is all part of the eCVT and hybrid system, it should be covered under the hybrid warranty. But like most things with dealers you may or may not need to fight with them to make sure it gets covered

Ideally: Get something like the OBDLink EX and use Forscan (Windows and Apple/Android versions of the software are available). The OBDLink EX will read all the CAN buses in the C-Max and is highly recommended by the Forscan devs. Forscan will be the best tool to interact with and get access to Ford specific data and service procedures.

As the others have alluded to, the recommended option by most is doing a Sync 3 upgrade. If your C-Max already has the 8" touch screen, it makes such an upgrade super easy. You can look around on the usual sources like Ebay and Amazon and such. Many sell pre-programmed kits with everything you need and it is 99% plug and play and retains all factory features. Depending on whether you get factory nav or not (the built in factory nav is NOT required for using CarPlay or AA with their own nav apps like Waze/Google Maps/etc) will affect the price but you can expect numbers around $500-$700 on average. Sync 3 is a lot more stable and performant than Sync 2/MyFord Touch and you get the bonus of CarPlay and Android Auto. If yours has the smaller 4" non-touch unit, it'll be a bit more involved as a different wiring harness and dash components are needed to start. I'm not familiar enough with this particular upgrade path to give you specifics and those selling Sync 3 upgrade kits don't usually offer the extra parts needed to do a 4" to 8" upgrade.

This. Forscan will show you basically anything you'd ever want when it comes to Ford vehicles including their own proprietary DTCs/trouble codes that generic handheld readers will often miss. One thing to keep in mind is there are multiple CAN buses in these vehicles. Most cheap Bluetooth adapters will only read the HS-CAN bus which will at least cover the important stuff the engine, transmission, hybrid system, HVB, etc.. Other less critical systems like drivers/passenger door modules, parking aid system, climate control, etc. will be on the MS-CAN bus. For your needs this is probably not an issue, but this is merely an FYI. Forscan will still work just fine with these Bluetooth OBD2 adapters for basic diagnostics. In fact I keep one of those cheap low profile HS-CAN only adapters in my car at all times if I need to diagnose anything on the spot. I then leave my OBDLink EX for more 'heavy lifting' like firmware updates.

If the car was left to sit for 3 months untouched, you likely need a new battery at this stage. Being sufficiently drained for that long probably damaged it in addition to its age so it won't hold much of a charge on its own.

Interesting. Just reviewed the workshop manual for the listed official process for latch replacement and it does involve removing/replacing the actual door handle mechanism so it wouldn't be farfetched at all that they would miss the touch sensor connector that they would have had to remove. Definitely worth it to be aware of if anyone gets this or related work done and the sensors 'suddenly' fail. Just for documentation purposes, I have posted Ford's TSB on this where they recommend to disassemble the handle and clean and use some coating on it. In my case this didn't fix it but if anyone else wants to try it. Here's the stuff I bought as referenced per the TSB: https://smile.amazon.com/dp/B01L1UFJ9E 14-0078.pdf

Since I've seen this post referenced in a few places elsewhere and this is a VERY old post with some inaccurate information, here's some corrections hopefully for anyone coming across this thread: An actual full on screen freeze where the entire system is unresponsive and stays on with the vehicle off is a rarity nowadays. IF this continues to happen, ENSURE your Sync system is fully up to date! Old versions of MyFord Touch/Sync 2 were problematic and most of the bugs have been sorted with later versions which you can download to USB on Ford's site and install yourself. Or worse you can work with your dealer. In the interim the proper fuse 67 (not 69) is the one to pull to power reset the APIM/touch screen. There's another fuse, #79 which is for the ACM which is another issue that's already been well documented (touch screen works but you can't change AM/FM/Sirius stations, change audio sources, etc..). As far as the comment about turning on the engine/ICE, this is -completely- unnecessary not only for this but just about any other electronic fix/workaround on these vehicles unless it is an engine/drivetrain specific issue that calls for this step. As far as the electronics go including the infotainment system, the car is on and operational when in 'Ready to Drive' mode. Whether the ICE is running or not, it doesn't care. Also the multi step process of starting the car, waiting, turning off, replacing the fuse, etc. is also unwarranted. Replacing the fuse whether the car is on or off can be done in one go without cycling the ignition. Leave the fuse out for a minute just to be safe and let the module drain off any stored power and reinsert the fuse.

Can't comment on it continuing to try and connect, though I think there's something in the AsBuilt about a retry count so it may give up after some tries? This is PURELY a guess. The module will still pull 12v power regardless. It is still used for the operation of the Value Charge and Go Times functions even with no active 3G service.

Someone had brought this up on the C-Max subreddit and I posted a long wall of text essentially detailing my own process when I tried to sort out the lock/unlock sensor in the drivers door handle in my Energi. Thought it might be worth reposting here as well just for documentation purposes since even Ford's own workshop manual doesn't go into the FULL detail that I feel is really needed after I had gone through this. As an FYI for those without the 'Intelligent Access' feature and no sensors in the door handles, the door handle replacement is a TON easier. Same process as laid out below, but ignore the warnings about the wiring since none of that is there. Sadly I don't have any pictures of the process, but I feel like I am acutely familiar with this now so feel free to toss any questions this way and I can try to answer them.

Having messed with this a bit in my recent inverter setup, I can say the big negative battery lead going from the battery to the bolt on the body middle-ish of the car back there is probably around 4ga. Visibly it's about the same gauge as the wire I used which is also 4ga. Can't say for the positive side since that one's not as straightforward. The main battery fuse/junction on the positive terminal of the battery actually splits right there between the DC-DC converter and vehicle electronic feeds. There's also plenty of resources/tables around the net detailing correct wire gauge sizing based on load and wire length. Nothing special needed for a hybrid vehicle here, the same concept applies. That said, if this was my own vehicle I'd focus on trying to fix the actual cause of your issues than a bandaid such as this. But that's me. Most of the common causes of issues like random battery drains or fob detection issues are well known and have solutions.

And here's the inverter side of things and the final hookup. All working smoothly. Couldn't test at its full rated power as I didn't have anything handy that could pull that amount. But tested with my gaming laptop and a crockpot pulling about 480-500w total and no issues. DC-DC converter was showing about a 50-60A load on the LV side and only around 3-4A from the HVB. Didn't even look like the 'Other' gauge on the IPC moved much. Also the voltage drop must be just about nonexistent which is a good sign. Inverter was reading the same voltage as what I read at the battery posts around 14.8v at the time. Cables remained cool under an extended test with the above half load. All in all a very clean setup and easy to store away keeping cables out of sight when not in use which is especially nice with cargo space at a premium already with the Energi. The original 'potential' use for this is coming up this weekend. Will need to see if the park we're going to and setting up at has working outlets. If not, it'll be this setup's time to shine and I'll definitely report back how that went. (Also realized the backwards posts on the inverter. The actual wires are correct, I was just dumb and put the plastic covers on backwards. It's since been fixed.)

For the most part, it seems the large majority of C-Max's (especially Energi models) were keyless entry/start equipped. Later model years Ford started to dumb things down and equipped them with traditional keyed ignitions on the base trims. 2017 was possibly the tipping point here. I'm sure earlier model years had some keyed ignition models but they were probably fleet/barebones models.

Sadly from what I've seen in the C-Max FB groups, it's not unheard of for people picking these things up used to either get mismatched keys/fobs, no physical backup keys, or incorrect backup keys. The dealers/sellers probably don't due their due diligence simply enough as long as the vehicle starts. So probably a good thing for anyone looking to buy a used C-Max to check on this straight away. I was also dumb and didn't check mine right away when I bought the car. I do have two backup keys and they are keyed correctly, however one doesn't have enough thickness filed off so it wont fit in the lock. Still haven't gotten it sorted mainly because the few local locksmiths I've checked won't mess with these style keys. Couldn't tell you why. ? Another potential thing that I've seen come up on those FB groups though I haven't had anyone 100% confirm the outcome: But the potential is there to be given a simple 3 button fob (lock/unlock/trunk) but have the vehicle equipped with remote start. A quick and easy check for new owners is using the vehicle settings menu in the left screen of the IPC/gauge cluster and there will be remote start settings there. If they are not greyed out and can be adjusted, your vehicle should be equipped. If you don't have a fob with the remote start button on it, bug the dealer/seller you bought it from to get the correct fob.

One caveat I will note is when attempting to use the big negative lug on the frame, you should still disconnect the negative right at the battery. The bolt used to go into the frame is very snug and long and relying on this to be your main method of a battery disconnect will lead to intermittent connections and sparking as you try to unbolt it (as I stupidly attempted to do the first time around). Disconnecting right at the neg battery post is cleaner and quicker. THEN you can unbolt frame lug. It was tempting to go that route especially being an Energi with all the ducts in the way. Even with those removed per Ford's workshop manual, the bolt on the neg terminal was still a pain to get to but was doable with an open ended wrench.

Got around to doing the most tasking part of this: Getting the actual vehicle-side wiring done. My original plan was to do a 'belt and suspenders' setup with a 150 amp fuse (included with the inverter I purchased) right off the battery and then a smaller 100 amp circuit breaker in an accessible location behind the rear fuse panel on the driver side as both protection and an easy to access switch to turn on/off power as needed. However I had a heck of a time trying to sort out how to mount the CB back there even though there are two bolt holes in the body (one is being used as a grounding point for some circuit). I changed it up to make it a little easier to get wired and I'm just running the 100 amp CB right off the battery. SLIGHTLY more difficult to access but not by much. It can still be accessed via the small plastic panel covering the battery (on the Energi this is the one that holds the fuel funnel) so just need to empty out the cubby to get to it. No tools needed or bolts/screws removed. I've attached photos of the wiring and routing below. Grounding point was easy. Factory, Ford has a big beefy (looks to be about 4awg based on my own wiring which is also 4awg) ground cable going from the battery to the body. This is also the ONLY ground connection from the battery to the rest of the vehicle it looks like. I ran the ground for my inverter circuit here and placed the lug on TOP of the existing factory lug just to ensure it still maintains solid contact to the body. The positive wire I had to figure out how I wanted to run this and hopefully keep the rest of the vehicle happy. One of my main concerns after reviewing wiring diagrams is there's a 150 amp maxi-fuse that sits between the battery positive and the leads to not only the DC-DC converter but the rest of the vehicle electronics. In the one picture below, this is buried inside the big red plastic cover on the battery. Since I already essentially have fused protection with the CB, I connected it before the factory 150a fuse so it is able to pull surge power if it needs to straight from the battery without risking blowing the factory fuse (which seems to be hard to find and not sure if it is a standard off the shelf fuse type). Same as the ground lug, I kept this above the existing mating surfaces so the factory mating and thus current handling capability should be maintained. This is all ran via 4awg wire over to the driver side and up in the cavity where the rear fuse panel is located. Wired into a beefy Anderson style quick disconnect (which comes with a cover that is tethered to it to keep things safe when not in use). Right now the CB is just floating there and not secured, though I'm probably going to find some heavy duty velcro and just secure it to the top of the battery. I tried and spent probably a good hour or two trying to locate a more secure mounting solution that still remained accessible but had no luck. There's ample room behind all of the plastic trim panels. None of the wiring is interfering or has a chance of being pinched or rubbing through other parts. Even the cavity behind the driver side trim panel with the rear fuse box has lots of space. The picture showing that looks messy but that was a rough 'shove it in there to button up the car' deal but I can easily slide the QD and wires out of the way of the fuse box. I do plan to get some corrugated wire conduit like Ford already uses on much of the wires back here for extra physical protection. Next up is to wire the other side of the QD to the inverter and test. I'll report back when I get to that stage.