HVAC FAN SPEED VARIATION

[BlownGP]

So, still no definite fix for this?

Mine has been doing since I bought it used last year. But it started today to now just blow a little air no matter what speed is set.

This going suck, when it's about to get hot here.

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[BlownGP]

I decided to take it back apart, and look at the circuit board built in to the "Media Center" or whatever Ford calls the radio, and I believe the issue is in that board- the one with the radio components.

I just read this. Do you mean the ACM? The box that site below the radio.

Mine still has this problem and it seems whatever fan speed I set it when I start the car. That's what it will stay on. Won't go higher, won't go lower.
Thank GOD it's ice cold but talk about annoying.

 

[HotBadgerFart]

I just read this. Do you mean the ACM? The box that site below the radio.

Mine still has this problem and it seems whatever fan speed I set it when I start the car. That's what it will stay on. Won't go higher, won't go lower.
Thank GOD it's ice cold but talk about annoying.

No, the actual board backing the HVAC controls.

 

[Cobra Jet]

In older vehicles when the fan speed started to either loose speeds, not turn on or vary in setting operation the fix was to replace a resistor block that was usually mounted to the HVAC box or found behind/under the glovebox.

The only other reason I can think of the fan motor varying in speed (besides a bad board), would be the motor itself is shorting out or has some other type of internal issue.

For those under warranty, I’d take it to the Dealer and see what their diagnosis turns up. For those out of warranty, do some pinpoint tests on the leads coming off of the motor to checking for resistance measurements.

I know the HVAC also has actuators for various internal “doors” that if an actuator craps out, it could prevent proper airflow through whichever vent depending on HVAC setting. These are common failures in the HVAC system of most modern vehicles today.

 

[BlownGP]

No, the actual board backing the HVAC controls.

Well, now you have be curios. I have a spare dash bezel for brother because we are about to do the base to sync 3 upgrade.

It's from 2015 so it might have the same problem. Which I hope not because my brother would be pissed. lol.
But I'm going to swap it out and see what it does.

 

[BlownGP]

In older vehicles when the fan speed started to either loose speeds, not turn on or vary in setting operation the fix was to replace a resistor block that was usually mounted to the HVAC box or found behind/under the glovebox.

The only other reason I can think of the fan motor varying in speed (besides a bad board), would be the motor itself is shorting out or has some other type of internal issue.

For those under warranty, I’d take it to the Dealer and see what their diagnosis turns up. For those out of warranty, do some pinpoint tests on the leads coming off of the motor to checking for resistance measurements.

I know the HVAC also has actuators for various internal “doors” that if an actuator craps out, it could prevent proper airflow through whichever vent depending on HVAC setting. These are common failures in the HVAC system of most modern vehicles today.

I'm out of warranty so I know I'm screwed.
Yeah, I've had the blend doors not work on my older GM cars. Shitty ass design.

I too thought it was the blower motor. But I dunno. It's hot has shit here, so I have to keep it on 4-5 fan speed anyways, but still sucks.

 

[Black19GT]

My ‘19 GT has done the same thing since new. Fluctuates up and down on its own like it can’t find the proper setting or something.
Just haven’t wanted to be without my car for any period of time while they fix it lol

 

[BlownGP]

Well that's wild the it's still happening on a 19.

My brothers 16 base doesn't have any issues. Wonder if it's a premium issue.

 

[Tobey]

Well that's wild the it's still happening on a 19.

My brothers 16 base doesn't have any issues. Wonder if it's a premium issue.

Nope. My '16 base does it as well.

 

[BlownGP]

Ok, well that settles that. lol

Thanks

 

[Deleted member 35786]

I do hear mine go up and down a bit when its running. Nothing really that bad but I can hear it once in a while. It is still blowing cold so that is most important! LOL

 

[BlownGP]

Mine does that, but mine won't change speeds. If it's at 6-7 it will stay that high even when it shows it's at one. So I dunno. lol

 

[Deleted member 35786]

Seems they have had this issue on the previous generation stang as well.

Found this on repair pal:
https://repairpal.com/ac-fan-speed-changing-constantly-690

Problem Description
The 2010-2014 Ford Mustang GT with automatic climate control may have a problem with frequent fan speed changes when using the heater or air conditioner. This includes all performance models including the GT500, BOSS 302, GT, GT350, GT-H, and CA Special Ed.
Normally, the fan speed changes only to maintain a selected temperature, but when the fan speed changes frequently and needlessly, there is an issue with the fan speed control unit.
The fan speed control unit, sometimes erroneously called the blower motor resister, regulates the speed for the blower motor in order to maintain the temperature set by the driver. When it fails, the fan will run at random settings, and the climate control will be inaccurate.

Note: this does not affect the temperature of the air that comes from the vents, it affects the amount of air that comes from the vents.
The repair is simple, and quick. The control unit is located behind the glove box in most models, and removal and installation takes only minutes.
Also note: this only applies to vehicles with single or dual automatic climate control.


Anyone find a fix yet?

 

[BlownGP]

Seems they have had this issue on the previous generation stang as well.

Found this on repair pal:
https://repairpal.com/ac-fan-speed-changing-constantly-690

Problem Description
The 2010-2014 Ford Mustang GT with automatic climate control may have a problem with frequent fan speed changes when using the heater or air conditioner. This includes all performance models including the GT500, BOSS 302, GT, GT350, GT-H, and CA Special Ed.
Normally, the fan speed changes only to maintain a selected temperature, but when the fan speed changes frequently and needlessly, there is an issue with the fan speed control unit.
The fan speed control unit, sometimes erroneously called the blower motor resister, regulates the speed for the blower motor in order to maintain the temperature set by the driver. When it fails, the fan will run at random settings, and the climate control will be inaccurate.

Note: this does not affect the temperature of the air that comes from the vents, it affects the amount of air that comes from the vents.
The repair is simple, and quick. The control unit is located behind the glove box in most models, and removal and installation takes only minutes.
Also note: this only applies to vehicles with single or dual automatic climate control.


Anyone find a fix yet?

Ohh god. This sounds like my Grand Prix all over again.. Fuckin 2015 and still can make a good blower motor resister. lol

I didnt have fan speed issue with the Grand Prix. It would hot on one side and cool on the other.

I guess for $26 it's worth a shot. I wonder if it's still behind the glove box.
https://shop.advanceautoparts.com/p...5-P?navigationPath=L1*14922|L2*15019|L3*15900

 

[Deleted member 35786]

I think the fan speed control unit is actualy called a control module. It is No. 7 in this diagram. Correct me if I am wrong though.. Question is the location in the car, anyone have any idea?
https://www.tascaparts.com/auto-par...gas-engine/hvac-cat/blower-motor-and-fan-scat

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