AC stopped working when stopping at red light

[Hellwig]

When I stopped in front of a red light, the AC turned itself off. I tried to bring it back on, but it didn't work. Meanwhile, I noticed the auto start/stop function stopped working as well. When the vehicle moved again on green light, the AC button worked again when I pushed it, as well as the auto start/stop function. And the same situation happened again on the next red light. I just purchased the vehicle on last December, so I highly doubt this is caused by low battery voltage. Another weird thing, the passenger seat heated itself even when the heat switch was off back to Feb (Engine was running). After I shut off the engine and then restarted next day, everything worked fine. Furthermore, in the 5 months of my ownership, the back door couldn't automatically open itself for at least three time so far. And then it fixed itself after restarting the engine. What the heck. Ford, please hire more competent programmers if you prefer keeping sync 4/4A.

 

[Hellwig]

I just now used Forscan to check the DTC codes. It gave me more than 10 codes in more than 10 different modules. But I believe the root causes is Lost Communication with Front Interface Module A with the PCM module. I cleared all these codes and test drove it for 5 miles. And then scanned it again, there is one DTC code on ABS module reappearing as below:

Code: U0415 - Invalid Data Received from Anti-Lock Brake System (ABS) Control Module 'A'

Status (-2E):
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

Module: Power Steering Control Module

Honestly, I don't think there is any hardware problem on PSC module or ABS module. I will delete the code and retest it tomorrow if time allows.

 

[Hellwig]

Deleted the DTC code and then drove 4 miles back and forth. Scanned again and there was no code. Just a software glitch.

 

[techdude99]

That's several glitches. Happy to hear it seems fine. Let us know if it happens again.

 

[Hellwig]

Update: I blamed Ford erroneously and it was my mistake. It turns out that the lower connector on the Start/Stop eliminator device was loosen. After I re-connected it, everything works just fine.

 

[Mr Big]

This can happen when the battery gets low. I was using FORScan and forgot my A/C and auto lights were on and killed the battery. I charged it back up and drove it, and it idled an shifted rough, one running board was stuck open, auto start/stop did not work and more. I hooked up FORScan again and there were all sorts of codes, including catalytic converter. I cleared the codes and wiped the learning data and everything went back to normal.

 

[rd618]

These things are crazy sensitive to voltage discrepancies. You’d almost think they would do redundant checks before flagging a code. But I’ve had 5-7 codes appear even when the battery is at 60% SOC. they go away after I put it on the trickle charger for a few hours.
And for context my battery is just short of 2 years old.