Low idle/stalls with ac on

[Ctakacs9]

2007 Edge SEL

When I'm idling with the a/c on, the RPM occasionally dips down really low and will sometimes stall. It runs fine as long as I'm driving, it's only when the car is stopped. If it does stall, I can start it right back up. 

I cleaned the throttle body about a year ago (it wasn't even really dirty but I did it anyway) when I replaced the spark plugs. Any ideas on what could be causing the low idle/stall only with the ac?

[DILLARD000]

3 hours ago, Ctakacs9 said:

2007 Edge SEL

...idling with the a/c on...RPM occasionally dips down...sometimes stall

...fine as long as I'm driving...only when the car is stopped

...If it does stall, I can start it right back up

Sounds suspiciously like same problem I had a couple of years ago on a 2008 Edge SELAWD.

With AC on, engin RPMs would randomly dip momentarily or engin may fully stall when at a Stop Sign\Light, then engin would start again fine

Was not getting any OBD2 TroubleCodes at all, so it was a matter of replacing parts 1 at a time until I found something that helped.

Turned out to be the damned Radiator FanControlModule was randomly shorting out the fan speed signal wire from the PCM\Computer,

causing the PCM to die momentarily;  tried several cheaper aftermarket FCMs (Gates, Dorman...), found them not fully compatible with PCM,

so recommend only using OEM Ford part MotorCraft# 7t43-8c607-ag \ 7t43-8c609-ab \ 7t4z-8b658-a;

this is the FCM for the 2007~2010 Edge without a TowRated Radiator package.

Be ware the local parts house (Oreilly, Advanced, ...) & Amazon\Ebay will try to sell you an aftermarket offbrand version;

there is confusion\misinformation amongst both manufacturers+vendors on compatibility of this part.

FCM is mounted on upper left corner of RadiatorFanCowling, plugged into VehcileHarness & FanHarness.

 

 

 

Edited July 15, 2023 by DILLARD000

[Ctakacs9]

Awesome - thanks for the reply. Was it easy to replace?

[DILLARD000]

13 hours ago, Ctakacs9 said:

Awesome - thanks for the reply. Was it easy to replace?

Yep, about 30minutes, easy to replace:

* Unplug MAFSensor on AirDuct

* Remove top+bottom of AirFilterBox with AirDuct+MAFSensor to get it out of the way

* Unplug VehicleHarness side of FanControlModule

* Unplug FanHarness side of FanControlModule

* Install new FCM & re-install above items

Basic test of new FCM:

* Start Engin cold, idling with AC off: RadiatorFans should be off

* Switch AC on to minimum cooling, 1st position left from center, temp control on cold: RadiatorFans should come on 25%Speed or faster

Full test of new FCM can be done with ForScan on a Windows Laptop & an OBD2~USB module like the OBDLink#EX.

 

Video on replacing the FCM, though recommend a MotorCraft part, not Gates:

 

Edited July 16, 2023 by DILLARD000

[2015Edge2015]

Hmm... I wonder if my 2015 edge 2.0L has this same part and fault. My AC dips my rpm at adle aswell. Anyone have this experience on newer models?

[Ctakacs9]

On 8/11/2023 at 2:09 PM, 2015Edge2015 said:

Hmm... I wonder if my 2015 edge 2.0L has this same part and fault. My AC dips my rpm at adle aswell. Anyone have this experience on newer models?

Did you ever figure out a solution for yours?