09 expedition AC Warm at idle, cool while driving.

[max78]

Temps are starting to climb here and we hit 100 degrees last week.

My first thought is a weak cooling fan but I'm not sure. I do not have any overheating issues or anything.

When I start it I can sometimes hear the fan but not every time.

When I turn the AC on I can hear the fan kick on a little. It sounds like maybe it's on low speed.

Is there a connector I can pull to force the fan to run locked up/full speed so I know for sure it's working as intended?

I'm thinking maybe the coolant sensor?

 

[stamp11127]

Plenty of threads on here about ac issues. First thing to check is the airflow through the condenser/radiator. Wash both with low pressure water to remove any dirt or sand.

After checking the wiring diagram, Ford in their infinite wisdom now controls the climate system with modules. Fan speed is now under control of the pcm.

After those are checked the next item is the system pressures at rest and at idle for the specific ambient temp they are checked at.

If the pressures are correct then it is time for a scan with a high end scanner.

 

[ExplorerTom]

Does a 2009 have a mechanical or electric fan?

If it has a mechanical fan, turning on the AC doesn’t turn it on like an electric fan. It will only engage as the clutch warms up from the additional heat transfer.

My 2000 was the same way: frosty AC while moving but warm and pathetic in traffic. I replaced the mechanical fan with electric fans. Now I have cold AC at idle. I replaced the fan for a different reason though.

 

[max78]

Does a 2009 have a mechanical or electric fan?

If it has a mechanical fan, turning on the AC doesn’t turn it on like an electric fan. It will only engage as the clutch warms up from the additional heat transfer.

My 2000 was the same way: frosty AC while moving but warm and pathetic in traffic. I replaced the mechanical fan with electric fans. Now I have cold AC at idle. I replaced the fan for a different reason though.

From what I understand it's a hybrid.

It's still a mechanical fan, but its electronically controlled. What I'm not sure of is how it works, is it still a viscous coupler that's prone to failing, or something else? To me it looks like is still a viscous coupler so that's why I was wondering if there was a way to force it "fully locked" or whatever.

 

[stamp11127]

https://www.rockauto.com/en/moreinf...np0vnyIfYEQBz8+IjsiQ8n7SoAg/lSzEDyYcpHXr35R8l

 

[Trainmaster]

Can these simple things get any more complicated?

 

[max78]

https://www.rockauto.com/en/moreinfo.php?pk=2420632&cc=1443966&jsn=447&_nck=ZExt1ysfqhqWnq+EvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86+AYIh/8vGRbRbhjtQtS85kRvd+HcYs0ObZkk208yYfTJPAScs7B+swxljvxsZkyWhAHAbckZiCm3zfD8aYwyjD/4enxFKjYl/dmMlt0mKoRwger49GJEZ/etd/VJKCwFVmALYd8tnU7Lt8oQeqEZSt1ZsCLtLGaQoOQUZY8psfp6x5zFuSrCt9GFAkwnDyt1EjBDTN/O5UGoTQATE0qeVWuln3+GjwyWXMfGwC1pw0x/XtvY3oLcf8vgnp0vnyIfYEQBz8+IjsiQ8n7SoAg/lSzEDyYcpHXr35R8l

Well look at that, I should read the rockauto parts descriptions!

Its a electronic viscous fan clutch, and dont replace without a trouble code (ya right!)

#2 on the how to detect a faulty fan clutch is poor AC performance at idle / low engine speeds.

 

[ExplorerTom]

Huh. Apparently they figured out a way to make a simple fan clutch more difficult.

You don’t want it fully locked. You’ll sound like a 737 taxiing for takeoff. Everywhere you go.

 

[max78]

Huh. Apparently they figured out a way to make a simple fan clutch more difficult.

You don’t want it fully locked. You’ll sound like a 737 taxiing for takeoff. Everywhere you go.

I know that, I just want to test it so see if it will fully lock up, because if it wont then there is an issue and it should be replaced. Most vehicles I have been around with any kind of electronic fan control, if the PCM looses coolant sensor it runs the fan full speed / lock-up, and was just asking the question before I start trouble shooting, I have been away from the truck. I will try it and it will probably throw a CEL but I can reset that.

Sometimes the fluid leaks out or breaks down and you get less engagement as they age. That means slower fan speed, but it can be gradual and you will get issues like warm AC at idle.

I will wash the condenser, check the pressures, and have my father-in-law scan it and maybe see if there is a self test that be performed.

I had my Jeep clutch fan lock up and it was miserable!

 

[Trainmaster]

What does that electronic, goo-filled POS cost?

It's computer controlled. Don't assume this is a simple on/off arrangement. This is designed for efficiency, not cold air conditioning. Tread softly before throwing parts at this thing.