Fan speed turning down on its own

[Grandaccess]

Mine does this too, so does the wife’s ranger, and my f550 work truck. From what I’ve read, the truck turns the fan down when you’re on the phone to reduce background noise. If you turn the fan speed back up once you answer the phone it should turn up.

Yes it goes back up manually, but I would think it would do it once I hang up automatically?

Sponsored

 

[GreyAreaRanger]

Is it kicking out of max on time out? I know when I had my escape it kept kicking off recirc so I checked into it and it had a timer programmed in to kick it off and let fresh air in so people don't pass out for lack of oxygen in the passenger compartment. Just something you can look into in the owners manual.

I’m not sure. I have manual controls, no auto anything. Today it did it once at a stop light when stopped. I didn’t see any loose connections Saturday when I went looking.

 

[airline tech]

Keep in mind that even the manual - climate system is still partially (Automatic) controlled by the FCIM.
Being that it appears that this thread has 2 scenarios- during and after calls - it’s normal operation to lower the fan speed , however it should resume the speed - after the call ends , if not then Sync is not releasing the handshake of the call - and still sees it as a active call.

If this is happening at a stoplight etc - then either ASS is triggering the drop or the FCIM is seeing a voltage drop , weak battery or low SOC and it’s lowering the fan speed to save battery (voltage) - so the question is what is the SOC and Battery Voltage- at the time of the event?
This will help isolate- battery voltage / charge issues vs actual blower module power issues
If bumps are triggering the fan speed to change- then there is a bad connection somewhere- creating a high resistance, this high resistance is what is causing the fan speed to drop at stops, you need to also note that the factory set SOC target will cause at idle charging to run strictly off battery and maintain about 12.2 volts, factor in a high resistance in the blower circuit and you may end up with say 10 volts on the blower- it cannot run full speed with that voltage

 

[Motorpsychology]

For the speed control issue, a remote possibility is that the brake switch is being tapped just slightly enough to disengage it, or maybe there's corrosion on or in the switch, where a slight bump will make internal contact in the switch and cut the cruise.

Maybe you could have someone follow you as you drive over this section with the cruise on and notice if the brake lights flicker

 

[airline tech]

I have checked the diagrams for any obvious standouts for a tie in to both that would ONLY affect these 2 functions - nothing stands out (YET) - so unless there are other symptoms - (anything) that flickers or noted inop - I do expect its pushing out a code that may help pinpoint it down and its most likely a Lost (Com) type code.

Plus - if you have the ability to - Live Data Monitor - all the modules have a - Module Supply Voltage or Similar PID - these can be monitored to see if the voltage is actually dropping - this would be beneficial data if you are using a plug in volt meter in the power point and it maintains above 12.2 volts at idle.
If we only focus on the - Blower Motor (Issue)
Then we have - Always Hot (Relay) - so main battery feed to the BJB and related cables and then the control side via the FCIM

Sponsored