On my 13 when they stuck on high it took 2 dealers to fix it. They replaced one of the fan relays and the dual fan setup. This was years ago. No I only see the high mode on hot days and when over hot asphalt. Mine is a 13. FYi

 

Historically (meaning all of the Fords I've owned with dual fans), both fans run for each speed setting. That said, I've not checked my F150. If I get a chance, I'll take a look.

 

Problem solved. I sold the truck in what appears to be a very lucrative pickup seller’s market these days. The main reasons I sold it were the A/C w/fans and the horrible brake system. Sorry, Ford, I didn’t get my money’s worth.

sorry I could help anyone here. I did replace the fan assembly. Though it had a bit more of a muffled sound, no difference in behavior.

 

I haven't heard anyone mentioning the AC High Pressure switch. A video show a mechanic (?) resetting the value for the switch with a Resistor Box. The pressure transducer acts as a 'load' (which is the resistor) in a regulated DC circuit. As the load changes (based on whatever physical force is being measured by the transducer), the voltage across the load changes. That resistor box can be wired in parallel to the load of the transducer to ultimately change the load. Those changes can be measured using a sensor and that sensor can essentially make decisions based on those changes in voltage. So, what the guy was doing was diagnosing - not adjusting. ie. All he did was change the load in that circuit (which changes the voltage to the sensor) to see how the sensor reacted to that change. In this case, a given voltage at the sensor translated to a physical force - PSI. Now he knows he's got a bad pressure transducer. Based on a quick Google search, it appears that this is a well-known problem with late-model Ford F-150's.

 

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Our 2004 or 05 Expedition had a same or similar issue, except that back then, they simply replaced the temp probe. Seeing the later year models that this TsB is for, I wonder if it is a result of their previous years complaints/efforts, 2011-2013 with cooling and fan running issues and poor ac performance, to finally address the issues. My 13 evap does not reach the design temp for it, like many others of that year model.

I wonder if the actual design for the probes operation is changed?

Thanks for posting this.