2018 Max HVAC issue

Zig10 said:

Could be a sensor or the controls, but I would have a mechanic throw a set of gauges on it to check the refrigerant charge. If it is running low the evaporator can freeze up and force the system into defrost mode, which effectively shuts off the cooling during that time. It's a pretty easy test.

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x5TA1NERx said:

OK. So this one is throwing me off.

About a month ago, the AC started to get warm after 20-30 minutes. This was also accompanied by a decrease in blower speed. Turning the system off for 5 minutes resets whatever was the issue. Was happening in the front and the rear. It does seem to get warm faster if it is hotter outside but I'm guessing that is my feeling of the system. We always left the system on auto but recently started doing the manual controls including max ac/recirculation.

Through time, the issue has continued the same except now the rear won't even have any airflow coming from the vents.

I was originally inclined to believe it to be a sensor somewhere going crazy after 20-30 minutes but the no air in the rear is throwing me off. Could it be the dash control unit or something I'm completely missing?

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99WhiteC5Coupe said:

TSB regarding poor A/C performance and reduced airflow:

https://static.nhtsa.gov/odi/tsbs/2021/MC-10201612-0001.pdf

Was your vehicle built during the time span listed in this TSB: https://static.nhtsa.gov/odi/tsbs/2018/MC-10144223-9999.pdf

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x5TA1NERx said:

First one yes. Second one no.

Seems like this is a big issue for Ford. Lots of issues with the refrigerant and system in general.

I'll look more into the first one. Thanks for sharing.

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99WhiteC5Coupe said:

Big issue - yes.

On 8/26/2022, Ford issued a safety recall for the 2015-2017 Expedition and Navigator models to replace the front HVAC fan motor asssembly, due to it being a fire hazard while the engine is running. Parts will not be available until next year.

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x5TA1NERx said:

Thought I'd give an update as I was finally able to get it in.

They could not duplicate the issue with the AC so no fix was offered there. Also, they couldn't find the TSB in the database so the one you provided me, which I gave to them, was ignored. Claimed ford must have thought it was no longer the fix or that there is a different one coming. Instead came at me with this list. Claimed coolant was low and it looked low but bottle was still full. Cold level coolant was still within range so I have little faith in this assessment. I also fixed the hood latch with a shot of pb blaster.

I've always had some respect in the dealer but I think this seals it for me. Especially when I watched the tech remove the reservoir cap while hot and coolant sprayed out over all the parts he's suggesting to replace.

Agree about the blower motor but when I asked what steps were taken to diagnose he just said that it wasn't working. I asked if he checked the fuse and was ignored. I used to be a tech and carried 8 Michigan certifications. I take my cars in now because I don't do that anymore nor have the physical capacity to do most of these fixes do to back problems but I expected better today. Apparently, my mistake.
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