2013 Fusion doesn't switch off AC?

[jeff711981]

I have a 2013 Fusion that has automatic climate control. When I turn it off and switch off the AC but leave the blower on to get some air movement, the air feels unusually cool. So cool in fact that I doubt whether it's actually turned off the AC. Because the Ecoboost engine is nice and torquey, I never notice the compressor turn on and off like I have in other cars with small engines, and I haven't actually opened the hood and attempted to confirm whether the compressor is cycling or not - that'll be my next step, but has anyone else noticed this?

[drolds1]

You might want to see this thread.

[Waldo]

Yep, get the FCIM software updated.

 

The A/C compressors in most new Ford's don't cycle anymore. They are variable displacement, so they can change their output to match cooling demand, but you will never hear them cycle.

[jeff711981]

Yep, get the FCIM software updated.

 

The A/C compressors in most new Ford's don't cycle anymore. They are variable displacement, so they can change their output to match cooling demand, but you will never hear them cycle.

 

After reading the thread drolds1 linked, I don't understand what the FCIM software updated would do. What is it designed to fix? The fact that turning off the AC doesn't turn off the AC?

[akirby]

Yes

[cygnet1]

Yep, get the FCIM software updated.

 

The A/C compressors in most new Ford's don't cycle anymore. They are variable displacement, so they can change their output to match cooling demand, but you will never hear them cycle.

 

I would like to know more about what this means. When the compressor is, say, running at half its maximum displacement, does it consume half its maximum power? When I use A/C, I don't like to leave it on all the time, thinking this is very inefficient when I need only a few degrees of cooling. I was under the impression that the A/C compressor works at 100% displacement whenever it is turned on, and that its output is mixed with hot air from the engine to achieve the desired temperature. For this reason, I have always set the desired temperature to the minimum 60 degrees, and manually cycled the A/C on and off to achieve the desired temperature, thinking this is much more efficient. Is this unnecessary?

 

This issue is particularly important to hybrid owners, for whom fuel efficiency is a primary concern.

[Mikey14SE]

The Externally controlled variable displacement compressors were designed to address exactly what you're talking about. There is the standard electrical connector for the clutch as compressors have always had. This engages the compressor when you actually turn it on inside the vehicle (and other times as well, ie defrost settings) There is also another electrical connector at the solenoid on a solenoid that is part of the compressor itself. That connector has 1 circuit powered with ignition on, and the PCM pulse width modulates the ground to determine the compressor displacement/pressure of the refrigerant.

 

The PCM uses inputs from the Evaporator Temperature sensor (low side pressure and evap temp are roughly similar under normal conditions) bussed in from the FCIM (acts as the HVAC module on 2013+ Fusions), the AC Pressure transducer (mounted in the high side of the system) and the Ambient Air Temp sensor to regulate the refrigerant system. The actual cabin temperature sensor info and other things have a slight effect on it as well, but the evaporator temp is the main input it looks at as far as regulation. It will still disengage the compressor completely at WOT or in cases of overheating, etc. High side pressure goes too high and the PCM speeds up the engine cooling fans to provide more airflow across the condenser to lower high side pressure, etc.

 

The compressor causing so much drag on the engine system that it reduces fuel mileage is nearly a myth in modern vehicles due to this design. It takes much more "work" to get the compressor spinning after the clutch cycles than it does to engage it once and keep it operating but regulate its output.

 

Hybrids use an electric compressor not even part of the gas engine accessory drive. Whole different "ball of wax" so to speak. This is so they can retain cooling effectiveness when the gas engine isnt running. They just speed up or slow down the electric compressor drive motor depending on pressures.

 

Oh, regarding the FCIM software update, I dont know exact specifics on what the software update actually entails, however i most likely addresses how the evaporator temperature sensor information is shared with the PCM to determine said compressor regulation.

 

Also Im sure you've probably taken this into account, but once that evaporator is cold and you shut off the AC, its going to stay cold for a time before the airflow across it warms it back to ambient temperature. Just saying its not gonna immediately give a non-ac type of output.

Edited February 14, 2015 by Mikey14SE

[Mikey14SE]

And on to my own rant about that other thread. I absolutely and wholeheartedly disagree with the statement that you cant shut the AC off at any time on these cars. That statement is just flat-out wrong. Regarding my 2014 at least.