A/C diagnostics questions

[ck80]

Do you live in or operate the car in overly dusty conditions? Try hising down the condenser (avoiding the fan motors as best as possible) to see if the head pressure drops, and be sure the fans are drawing through the condenser. DC motors will spin backward if polarity has been changed, be sure they aren’t “pushing” or attempting to push rather than pull. Those pressures almost seem like air was introduced into the system though, did you purge the gauge hoses of air? Just asking, because each hose is capable of holding an ounce or two of air, and if your charging handles weren’t seated when you hooked to the service ports, you may have introduced air which is a non-condensible…..which would lead to a high head pressure. Just tossing it out there.

We're in coastal Georgia, and the car has been operated on paved roads only since New. Aside from driving on the occasional road work zone through the years, it's never been exposed to much in the way of dustyness, and, certainly hadn't been in quite a long time before the failure.

Today was the first time in 160k miles any gauge hoses were connected to the system *to our knowledge* and, did evacuate the air in the manifold/hoses prior to cracking open the knobs at the lines. Did NOT add any charge to the system, so, whatever is in it is what it came with from Ford, absent any kind of system damage that could've introduced something or if some absurd thing happened while the car was in for service at a Ford dealer without our knowledge. When the car was under warranty we let them handle the maintenance so all intervals were computer documented in their system, and, if a claim had become necessary the only ones that could be blamed were them.

Aside from tires, a TB recall, an airbag inflator recall, and a hood replacement due to galvanic corrosion under warranty, the car has had nothing done but oil, fluids, and wiper blades. Not bad for 160k miles.

We can try taking a look at the fans and giving the condenser a rinse, but, I'd think water spray from driving would've taken care of that through the years and looking from the grille no noticable build up can be noticed.

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[spedy7]

With yours being a '16, I'd assume evaporator for one (problem years were '15-'17 for evaporator failures). Possible pinhole leak that sucks some air in when it was operating ok, and now overfilled the system with air. I've seen some with no visible leaks from the drain tube, but light up under UV when removed.

Two - and what we're seeing a lot of now on F150s - a biased evaporator temp sensor causing the evaporator to freeze. As I was explain to by an engineer - a frozen evaporator will cause the suction side to go into a vacuum and can pull air in through the compressor shaft seal, causing an "overcharge" with a ton of air.

With 1, you'd probably recover a lot of air but also a lower than spec charge of refrigerant. With 2, you'd have almost a full charge but get a lot of air with it. Did they tell you how much was recovered?