Those of you with the Auto climate control. When you turn the climate control on AUTO does the A/C indicator come on? If I turn it off and back on the A/C light comes back on, even if the temp is on 90! Is this normal? I dont remember the A/C light to come on when it was colder outside but now that its 60+ the A/C comes on whenever its on auto regardless of the desired temp.

 

The compressor is engaged in all modes except VENT, FLOOR, and OFF.

Check your owner's manual.

Steve

 

Yup this is normal. Auto climate control uses a mix of hot and cold air to get your desired setpoint. Compressor will be engaged no matter the setpoint, except on the above vent settings.

 

This drives me crazy, but ya it does engage the A/C down to a certain point. When it is about -3 Celsius (26 F for all you non-metric folks south of the border) or colder, then the automatic does not put the A/C on anymore. Seems like a pretty cold outside temperature to be before the A/C turns off.

Also, it seems to me I had it run once at -10 C. Led me to believe the truck had a humidistat sensor also and needed the A/C to de-humidify inside the truck. But I doubt Ford went that far on the HVAC system.

 

They didn't.

They just rely on the pressure drop of the contracting refrigerant to "cut-out" the compressor at low temps. Depending on the exact charge in the system, it usually takes place around 35-40F. Whenever the PRESSURE in the system drops to below 45 psi, the compressor drops offline...

 

Well that clears some things up. Thanks guys

 

I'm not so sure about that. Pressure on the system and turning the system on/off are two different things. My old GMC used to turn the A/C compressor on at any temperature (including -25 C). It was only on for 5-10 seconds, but it still went on. So did my Dads Chev. Ford has just decided to turn the entire A/C system on at a certain outside temperature.

 

Okay so this morning it was 47 F outside and when AUTO was turned on the AC light did not, after work it was 65. I again tried it and when I turned AUTO on the AC light came on. It must just be based on the outside temp.

 

My previous statement is correct.

There is no temperature sensing element or sensor in a Ford system that controls compressor actuation. Turning the system on and off (clutch cycling) is controlled by the PRESSURE in the system (some versions do add additional controls but they are not temperature related).

It's simple thermodynamics that acts on the cycling switch via the pressure in the system.

This ain't a GMC, in case you haven't noticed....

Steve

 

Have you taken your meds today?

 

Don't need any meds to:

1) Conclude you don't know the subject under discussion
2) Point out the obvious.

Go study. Come back later with an education.

Steve

 

I dont see the problem here... if u dont want the A/C on just hit that little A/C button. The AC turns off and the AUTO function still basicly works the same.
Just might take a couple seconds longer

 

The a/c also runs at colder temps to dehumidify. Helps keep the glass from fogging.

 

Same issue here too lately, I want the a/c on to dehumidify the cabin but because its so cold outside it wont come on, if I force it on via defroster, it just blows the front glass and takes forever to get the rears cleared up.... What else can I do?