AC/Heat fan randomly changes speed

[Geppetto]

On trips have noticed fan running on slowest speed (1), it will randomly ramp up in speed. Setting does not show higher speed but air volume and noise is definitely greater. Normal? 2024 lariat, not hybrid.

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[Sykotyk]

Were you on your phone? Is it set to auto? Auto doesn't care where it's set at.

 

[Geppetto]

Were you on your phone? Is it set to auto? Auto doesn't care where it's set at.

No and no.

 

[Mr Pibb]

No and no.

Eco mode will do it as well

 

[triangulumhalohydra]

This happens in my Mav and it's one of my few gripes (first world problems, right?)... It randomly ramps up to the equivalent of 3-4, even though it's set at 1. No clue what purpose it serves...

 

[Joester]

I set mine to "Auto" and let it do whatever. Keeps me comfy so eh.

 

[North1250]

I've noticed this also. Even my wife noticed! Suddenly cabin temperature changes.

 

[Sykotyk]

If it only happens when the ac is on it might be the evaporator or condenser are freezing up and it's defrosting

 

[Mox4615]

I’ve only noticed this when I try to use the phone and the air is on, it’ll drop the fan speed by itself. I assumed it did that to keep the person on the other end from sounding like they are inside a tornado

 

[MYMAVXL]

I might be repeating here…but happens to me with Auto set on…or when in Eco mode…or when I stop and Auto Start/Stop kicks in. If I disable all that stuff it works very predictably.

 

[colinl]

This happens in my Mav and it's one of my few gripes (first world problems, right?)... It randomly ramps up to the equivalent of 3-4, even though it's set at 1. No clue what purpose it serves...

it's smarter than you.

at least, Ford believes that they know how to manage climate in a vehicle better than fully manual controls, so they don't give drivers full manual control EXCEPT off. off is really off, anything else will enable the truck to figure things out.

when the humidity is high it can automatically turn on the air conditioner even if you've pushed the button to turn it off. let's say it's somewhat warm, but you find it still acceptable and you're trying to get max mpg without the ac compressor running.

when the humidity is high it can also turn off re-circulation. conversely, when the humidity is low, it will recirculate more and longer. automatically.

these things happen even if you have auto mode disabled. my suggestion is to enable auto mode and just dial in whatever temp. it is normal to change the temp setting a lot based on recent activity, clothing and solar intensity.

drivers have proven they do the wrong things with the HVAC controls very often. another popular thing for drivers to do is in the winter they will crank the fan speed for heat even though the engine coolant is not warm, and the heater core acts as a second radiator which makes the coolant warm up even slower. and obviously, blowing a lot of cold air is the opposite of what a driver wants when it's cold.

 

[Joester]

One thing I have noticed is that the controls will not use outside air for temperature management.
On a cooler day (example outside air temp is 65 degrees) and the vehicle has sat in the sun during working hours, I get in and start for home and notice the air conditioning is required to reduce the temperature to the 70 degrees I have the controls set to. Manually turn the A/C off and the cabin temperature will not reduce on it's own.
Yes - open the windows and blah blah... My allergies prefer at least some filtering through the cabin air filter in peak allergy season.

 

[LittleTrucker]

I might be repeating here…but happens to me with Auto set on…or when in Eco mode…or when I stop and Auto Start/Stop kicks in. If I disable all that stuff it works very predictably.

I noticed this and usually run in Eco mode. Anyone know why it happens in Eco mode?

 

[Carlitos_92]

One thing I have noticed is that the controls will not use outside air for temperature management.
On a cooler day (example outside air temp is 65 degrees) and the vehicle has sat in the sun during working hours, I get in and start for home and notice the air conditioning is required to reduce the temperature to the 70 degrees I have the controls set to. Manually turn the A/C off and the cabin temperature will not reduce on it's own.
Yes - open the windows and blah blah... My allergies prefer at least some filtering through the cabin air filter in peak allergy season.

My theory on this is that the ambient air gets warmed up a little as it navigates the cowl/firewall, so it probably has to be colder outside for the system to do what you assume it would as far as cabin cooling. At 65F it may not work, but at 45F I bet it will.

If you use the "auto" setting the other piece of it may be that the system wants to reach your temp setpoint as quickly as possible, and it can do that with 65F ambient air plus refrigeration faster than it could with just 65F air by itself. It will eventually economize if the conditions are right (turn off recirc, use the compressor less, etc), but it wants to get to 70F ASAP first.

 

[Sykotyk]

I might be repeating here…but happens to me with Auto set on…or when in Eco mode…or when I stop and Auto Start/Stop kicks in. If I disable all that stuff it works very predictably.

The ac compressor doesn't run when the engine doesn't run. This is for an ecoboost


Also, auto is auto. It changes the temp and speed to automatically adjust the output of the ac.

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