-40 Temp reading // No A.C.

[Trish40]

Last year on a trip I hit a Werewolf ( or a jumbo coyote). It damaged my front bumper cover before happily trotting off to find its next victim. I had the bumper fixed and everything has worked fine (to my knowledge) but last week the temperature started displaying -40 in 80 degrees weather. Turns out, when this happens my car gets to decide that I don't get cold air.

I have 2 kids. Have you ever traveled with 2 young kids who have come to rely on the little luxuries such as cool air and suddenly had it taken away the first week they've felt 80 degrees weather? My kids are Champs. They're handling it, but boy they have a lot to say about it.

So begins my Google descent. I replaced the ambient temperature sensor. I pushed all of the reset combinations for the a.c. I could find. I know it's not a Ford F150 but I figured worth a shot. Still the display remains at -40.

I cannot find much information on what this means and my bank account tells me I'm not able to afford a trip to a mechanic shop quite yet. Does anyone have any ideas or guidance on where to go from here? I've searched and read many forums, the car manual and called the shop. So far I'm not getting a lot of luck on what to do if you replace the sensor and it is still malfunctioning.

 

[Rick]

If the original work was paid for by insurance I would contact them and let them know the job was not completed correctly.

 

[peterk9]

Welcome to the Forum Trish.
I believe the issue is likely with the Ambient Air Sensor (C132) located at the front of the vehicle.

Ambient Air Temp - 2012 explorer Limited

All, Slight fender bender yday (5-10mph) to the front of the explorer and I thought only scratches and some bumper cover misplacement... got in this AM and outside air says -40, then reverts to "---". So, I'm assuming I've either broken or dislodged the outdoor temp sensor - however...

www.explorerforum.com

Ambient Air Temp Sensor Replacement

Removal NOTE: If replacing the Ambient Air Temperature sensor a reset must be performed. Select the A/C and Recirc buttons simultaneously, then release both, Within 2 seconds select A/C button again. With the vehicle in NEUTRAL, position it on a hoist. REFER to Section 100-02, Jacking and...

www.explorerforum.com

Peter

 

[ProjectSHO89]

-40 is the default reading when the AAT sensor is open-circuited as viewed from its PCM connection.

The problem is indeed with the CIRCUIT for the AAT sensor. Could be the sensor, the connector, the wiring, the connection at the PCM, or the PCM itself. It's going to require diagnostics by someone with a meter and a scan tool to pin it down without just guessing.

If you're up to tackling it, the diagrams and procedure can be provided.

 

[Trish40]

Oh goodness. I'm pretty sure this is way out of my element but I'm going to give a shot anyway. Cars don't really blow up anymore right? Lol.

I do have a scan tool.

 

[ProjectSHO89]

Start by using the scan tool to pull fault codes. Most likely, you'll get at least one related to the AAT sensor. Post fault codes and we can go from there.

 

[Trish40]

If the original work was paid for by insurance I would contact them and let them know the job was not completed correctly.

I got 2 main codes, p0073 and p0073 pd. It also has 02 sensor, misfire, 02 htr, egr, fuel, computers, catalyst. My gas light is on, because well I'm one of those. Lol.

 

[ProjectSHO89]

The P0073 is the one that you're interested in. The rest are the status of various OBDII readiness monitors.

I'll go dig up some stuff this morning and post it here later. On a different computer at the moment.

 

[Trish40]

Thank you! I appreciate your help!

 

[ProjectSHO89]

If you need clarification for anything following or get stuck, ask questions. While I'm an experienced electronics tech, I'm not so experienced at guiding someone new through troubleshooting.

The above posted diagram is for an earlier model than under discussion and doesn't exactly fit in this thread. The 2016 underwent an electrical system evolution that changed a few things from the 2015 and prior model years. Specific to this thread's issue is that the AAT sensor was relocated a bit and that there is an additional inline connector in the circuit compared to the previous layout.

You will also need a multimeter for the following. A basic usable one is under $25. You'll be measuring resistance so you may need to visit YouTube University for a primer if you're not yet experienced in using a meter.

First, the schematic. Red arrow points towards the sensor in the diagram. Schematic is the same for either the manual or automatic climate control systems. At the PCM, the connector designation is different depending on the engine (which we don't know) and the sensor uses a different pin for each variant.

Connectors of interest - C132 at the AAT sensor, C134 is a 20-pin inline connector organized in a 2x10 configuration, PCM connector 103 pins.

Diagnostic tips (mine).

1. Verify C132 is connected to the AAT sensor.
2. Locate C134. Disconnect it and inspect for corrosion or damage. Finding and getting access to this connector will likely be the hardest part of this job.
3. Carefully inspect the wiring between C132 and C134 for any damage. Given the history, I'd put this very high on the suspect list. If nothing visually obvious, go to 4.
4. Check resistance of AAT sensor using the chart of temperature vs resistance in the attached pinpoint intro. Practice on the removed sensor, if you wish.
5. Follow the pinpoint procedure as attached.

Diagnostic procedure (factory) - Attached as pdf files.