I have a 2015 F-150 lariat and my air condition fan keeps turning off by itself. The light is still on but the blower stops running. If I keep the fan speed on 4 or higher it works fine, anything lower and it turns off and on by itself. Anybody else have this problem or know of anything I can check?

 

You don't have Auto climate on by chance do you?

 

No I don't. I wish it was that easy

 

Fan speed controller is wonky.

 

Sounds like you are low on refrigerant and it is freezing up and turning off. Does the air coming from the vents get warmer/weaker before it turns off?

 

Know a part number?

 

It seems to work great all the time.

 

I do not, sorry.

It's not the a/c freezing up:

1) Their system is designed to reduce the compressor BEFORE moisture starts freezing on the evaporator.

2) Shutting off the evaporator fan when the evaporator gets too cold goes against a key operating principle for a/c systems. You keep blowing air across a too cold or frozen evaporator so it will absorb heat/melt off freeze. If you shut off the fan on a frozen evaporator, it will stay frozen for a long time.

A completely frozen evaporator core will cause a reduced air flow, but it will not stop completely as there is (limited) room for air to flow around the core. You will continue to get cold air from the vents, just at a greatly reduces flow rate. The air speed will transition over a period of a few minutes, this is easily differentiated from a fan that stops running, the airflow will drop to zero in just a few seconds.

 

Can you get a lariat without auto climate - wasn't sure that was a thing. Eitherway just to confirm. you mean the dial with yellow lights around - spin it right - fan increases speed an noise - lights up.

On the bottom of the scale the fan seems to die out on you.

2 questions - does the fan happen to come back up at some point? and does this also happen when you get on the phone? Reason I ask there is a connection with Sync and the AC system such that when you get on a phone call with a paired phone it will command the fan down to lower ambient noise. It then comes back up once you hang up. Now I swear this is only on auto climate cars but things change. Meanwhile it does seem as if the fan dies off completely when at lower levels. Up near high or with recirc on it's sort of like cut in half.

Now if that's not the case at all - and the fan doesn't come back up for you I suspect as said before the control panel. Are you in warranty?

 

I looked at the wiring book, I have a 2015 also with the manual heat controls. The fan speeds are controlled by the FCIM which is the piece in the middle with all the controls on it. One wire runs from it to the blower motor. When you turn the fan speed switch, all your doing is telling the FCIM you want a faster or slower fan speed, the FCIM then sets the power to blower to get what you want. I'm sure in a manual climate control, it does what you tell it to do without any inputs from anything. If it doesn't my guess would be the FCIM.
Have you tried to get any errors out the truck via the OBD plug?