Mach-Lee
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| TECHNICAL SERVICE BULLETIN Lack/Loss Of Heat And/Or Windshield Interior Fogging While Driving During Freezing Temperatures | 23-2088 17 March 2023 |
This bulletin supersedes 22-2182.
Model:
| Ford 2021-2023 Mustang Mach-E |
Markets: Canada, USA
Summary
This article supersedes TSB 22-2182 to update the Title, Issue, Action, and vehicle model years affected.
Issue: Some 2021-2023 Mustang Mach-E vehicles may exhibit a lack/loss of heat and/or windshield interior fogging while driving during freezing temperatures. This may be due to the heating ventilation and air conditioning (HVAC) control module software. To correct the condition, follow the Service Procedure to update the HVAC control module software.
Action: Follow the Service Procedure to correct the condition on vehicles that meet all of the following criteria:
Labor Times
| Description | Operation No. | Time |
| 2021-2023 Mustang Mach-E: Reprogram The HVAC Module (Do Not Use With Any Other Labor Operations) | 232088A | 0.4 Hrs. |
Service Procedure
1. Reprogram the HVAC control module using the latest software level of the Ford Diagnosis and Repair System (FDRS) scan tool.
NOTE: Recommend the customer use AUTO mode and adjust the temperature to maximize heater performance.
________________________
This is the HVAC update that appeared for everyone last week. This is a slightly updated version compared to Power-Up 3.6.1 released last fall and factory software on 2023's. This most recent version seems to include a few slight configuration tweaks compared to the previous version. This new TSB also mentions window fogging in cold temps, the previous did not.
Because the heater is a bit undersized in the Mach-E, below about 5ÂşF (-15ÂşC) heat becomes limited with 100% outside air. To combat this, the new HVAC strategy automatically opens and closes the fresh air door periodically in cold weather (so it operates in forced recirc mode). This increases heat output, but it also causes window fogging as humidity builds up in the cabin. This mode of operation is a fine balance between providing more heat and creating window fogging, so the fresh air door must be cycled carefully to keep the humidity level in check. The previous software version did improve heat levels down to about -10ÂşF/-23ÂşC (panoramic roof) or -19ÂşF/-28ÂşC (standard roof) in my testing, but some users reported fogging issues at times.
The latest version may tweak the parameters slightly to help reduce fogging further. I noticed in the previous version, the fresh air damper could remain closed a little too long and create some fogging before the next opening cycle. With wet floor mats and boots from snow, the fogging could be even worse. Hopefully this update helps reduce the fogging a bit more.
I've only had this latest version installed for a short time, too soon to really notice much difference yet. Unfortunately the really cold weather is behind us, so I won't be able to test in the extreme cold. Anecdotally, it does seem to tighten the humidity control loop a little more (there is a temp/humidly sensor above the rear mirror in the perforated cover), and may try to close the fresh air door more often for shorter periods. Unknown whether this would increase heat down to a colder temp than the previous version.
No major effects on en-route DC preconditioning in my testing, we are still stuck with the short 30 km geofence (the PCM would need an update to fix that).
I recommend everyone living in a climate zone 5 or higher (incl. Canada) to get this update. Unknown whether it will happen as an OTA, might take a while.
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