Is AC tied to external temp reading?

[Scott Stokley]

All right I have something strange going on and I need some outside input. The external temperature reading on the center display above the radio is going crazy. It will go from reading the correct outside temperature down to -30 or -40°. When it drops past the 32° freezing mark the air conditioning cuts off. If I drive it for a few more minutes the temperature will slowly correct itself and as it rises past the 32° freezing mark you can hear the compressor kick on and you can feel the cold air coming out of the vents again. It appears that the AC is somehow being controlled by that temperature sensor? It doesn't make sense to me but that's what it's been doing now for about two weeks. The system is not low on Freon, because once I get up to speed on the interstate, the temperature reading will be steady at the correct outside temperature and the air conditioning will run perfectly fine for hours on end. Has anyone heard of this, experienced this, and figured out how to fix it? I spoke to my local Ford dealership and they have never heard of this. I'm just afraid if I take it in for repairs they won't be able to duplicate what it's doing. Help!

[mrtn]

Probably just a faulty thermistor.

[jrm223]

Actually, it's a simple fix with a part that's like $8 - the "Ambient air temperature sensor". Look at the pics in my gallery, I have a 2015 XL so my thermometer display is behind the steering wheel, but it's the same issue. The computer will disable the compressor below around 40* or so (from what I've read elsewhere) to prevent the AC system from literally freezing, because the computer 'thinks' that the outside air is actually that cold due to the faulty sensor. Another guy here had the problem shortly before my van did.

My dealer had my van for two days, but the assigned technician was off work one of those days, go figure. It takes them a couple hours for the job - pull the front bumper off, replace the sensor, reassemble. 

[Scott Stokley]

Thank you jrm223!  I knew it had to be something simple like that!  Is this something that I could do myself? I'm a mechanical engineer and pretty handy. I have the XL also so I'm certain this will fix it. I did get an extended warranty with this van because of the miles I drive, I've had it 13 months and I've already got 54,000 miles on it. Thanks again so much for your input, I appreciate it.

[jrm223]

On 7/26/2016 at 5:09 PM, Scott Stokley said:

Thank you jrm223!  I knew it had to be something simple like that!  Is this something that I could do myself? I'm a mechanical engineer and pretty handy. I have the XL also so I'm certain this will fix it. I did get an extended warranty with this van because of the miles I drive, I've had it 13 months and I've already got 54,000 miles on it. Thanks again so much for your input, I appreciate it.

I'm sure you could do it yourself, just a matter of finding the right replacement part. Your profile says a 2010 TC, so it may be a different part # than what my van uses (2015 TC Gen 2). Man, I thought I do a lot of driving! I had something like 32K at 13 months, now at 33,5xx at 13.5 months. 100 miles/day for work commute and I've driven to Nashville & middle Texas, too. 

[Osco]

My second sensor Has failed,, lasted about 15 months,,

Oh well,

Fords better Idea will cost me another $225 as I cannot do the work myself....

On a second failure and no re-design Ford should pay for this re-repair In Full.

But No, they want more money so they Engineer things like this repeating common failure..

and make no attempt to put out a permanent fix.

Shame on you Ford..

[Robert Smith]

My work vehicle doing the same exact thing.  Only at 20k miles.  Good to know it is the sensor and not some weird grounding issue.

[Sewerynek21]

Guys need help. I have 2015 van 250 and it outside teml drops to -30,-40 and slowly correct its helf anfter driving for about 2 minutes. I replaced ambient temp sensor and pugtail bit still same. Sometimes reads  actual no temp on start up, but sometimes starts at -40, -30.

 

anybody had rhis happen. Not sure if my gauge cluster is faulty

[PhotoAl]

I would carefully check the connection for loose or corroded connection.  Not sure what the sensor type of device the sensor is but thermistors and red can be more sensitive to connection issues.

[Don Ridley]

The outside temperature has programming that keeps it from reading temperature immediately. There are several routines or algorithms that require driving at normal speeds before it updates. This prevents reading the temperature of a sensor parked in the sun for hours or reading radiant temperature from hot roads and cars in stop and go traffic.

 

This does not explain the -40 readings. You need to troubleshoot the sensor by measuring the resistance of new and old sensors. There may be a problem with the input channel on the module. You may have a simple problem like a weak battery that is causing module errors. Reading DTCs with a scanner or Forscan Lite may help.

[Don Ridley]

Additionally, you can read the PID for outside temperature to see if the sensor is working. But I don't know if Torque or other OBDII apps read the raw data or the output from the vehicle's programming.

[Sewerynek21]

Ok. So i have ford ids and pcm sees outside temperature correctly in the Pcm. Its like the gauge cluster does not update correctly. Strange. Im scratching my head on this one.

 

I installed new sensor in the bumper with pigtail. Pcm sees Ambient temp fine, cluster looses its readibg at startup Sometimes, after driving for half block it gets up to actual temperature.

 

anybody have any ideas?

 

anybody have a pin out for the gauge cluster plug?

[Sewerynek21]

Also today for service wroter told me that, the last readibg before key off gets saved to gauge cluster, then when van gets restarted after a while it updates the temp. That almost sounds like the gauge cluster is loosing its saves temp value in memory?

[Sewerynek21]

[Don Ridley]

Reading your post again I think you have a Transit, not Transit Connect. You need to learn if the temperature is managed by another module ( like IPC instrument panel cluster ). Maybe this module needs to be reset or reprogrammed. 

 

If you have a Transit you may find better help on that forum.

[PhotoAl]

My TC lives in the garage and a couple of times this winter Ive noticed that the temperature takes a while to update.  If it 55 or 60 in the garage and 30 outside it takes longer than I would expect for the temperature to update.  May be the location of the temperature sensor.  With a 20 or 30 degree difference its easy notice.  

[Don Ridley]

From the service manual:

 

Due to the location of the Ambient Air Temperature (AAT) sensor in the RH exterior mirror area it is greatly

influenced by heat generated from inside the mirror. For this reason the outside air temperature value displayed

in the IPC does not update in the upward (hotter) direction under 33 km/h (20.5 mph). This update strategy is

used because the PCM is unable to determine whether the increase in temperature is truly from an ambient

temperature rise or by heat generated from inside the mirror.

The outside air temperature display in the IPC updates in the upward (hotter) direction under either of the

following situations:

if the vehicle is driven over 33 km/h (20.5 mph) continuously without the vehicle speed dropping below 33

km/h (20.5 mph) for approximately 90 seconds.

if the vehicle is allowed to sit with the engine off for approximately 6 hours (the outside air temperature

display in the IPC immediately updates to reflect the current ambient conditions since the engine has

cooled sufficiently and no longer has an effect on the outside air temperature sensor reading).

NOTE: If the vehicle speed drops below 33 km/h (20.5 mph) before the outside air temperature display in the

IPC begins to update, the PCM logic resets and the time starts over.

Because this filtering strategy exists, it may be necessary to drive the vehicle continuously above 33 km/h (20.5

mph) for approximately 90 seconds when observing the outside air temperature display operation. After the

vehicle has been driven above 33 km/h (20.5 mph) for 90 seconds, the outside air temperature display in the IPC

should start to filter upward toward the actual outside air temperature. Depending on the difference between

what the outside air temperature is displaying in the IPC and the actual outside temperature, it can take several

minutes for the outside air temperature display in the IPC to reach the actual outside temperature.

[Fifty150]

On 2/13/2019 at 1:46 PM, Sewerynek21 said:

 I have 2015 van 250

 

On 2/14/2019 at 6:55 AM, Don Ridley said:

Reading your post again I think you have a Transit, not Transit Connect.

 

 

You're probably correct.  He is either talking about a Transit 250, or Econoline E-250.  

[Fifty150]

11 hours ago, Don Ridley said:

From the service manual:

 

Due to the location of the Ambient Air Temperature (AAT) sensor in the RH exterior mirror area

 

 

 

 

Interesting location.  So you would have to remove the passenger side door panel, then remove the mirror, in order to service?

[jrm223]

On 2/15/2019 at 9:09 AM, Don Ridley said:

From the service manual:

 

Due to the location of the Ambient Air Temperature (AAT) sensor in the RH exterior mirror area

 

Is that for the big Transit service manual? Or perhaps the TC1 instead of TC2? This is some screenshots from the 2014 2nd-gen TC wiring diagram and shows the AAT right at the front bumper. I attached the PDF itself, for anyone interested you'll find this wiring diagram on page 14 of the PDF. 

 

2014_Transit_Connect_v1-0.pdf

[Don Ridley]

This is the big service manual for a 2016 TC. But I think you are correct, the sensor is in the front bumper. Musy have been a copy and paste error from another Ford. But the temperature display scheme seems to be accurate for the TC.

[DonShockley]

Here's the sensor location shown in the wiring book for my 2015.

C132 Ambient Air Temperature Sensor

[Sewerynek21]

Yes i have a 2015 transit 250 van. 

 

I need some wiring schematic help.

 

im looking for the AAT wiring and gauge cluster wiring

[Sewerynek21]

Ok so here is whats going on.

 

if u shutoff the van 2-3 time in a row it will show -40f in the cluster. If ypu drive away after 90sec or so the tempretature will read the actual outsode temp.

 

seems like thatupdate temperature part works correctly, however why does it go all the way to-40 in the cluster? Almost seems like the cluster cant remember temp on key off.