Will the Heat Pump system in the Fathom be as complicated as the one in the Mach-E?

[onuiebvbevnulib]

Take a look at this article on the Mach-E Forum:

2025 Mach-E Heat Pump Technical Info

Information on the new heat pump has now been published. It is a vapor injection heat pump which means it's capable of operating at low ambient conditions. In short, the new heat pump system is very complicated. It can operate in 8 different modes.

Note this:

The Ford Vapor Injection Heat Pump (VIHP) system is primarily managed by one dedicated local control module known as the Heat Pump Valve Control Module (HPVCM).

Control System Overview

• HPVCM (Heat Pump Valve Control Module): This dedicated unit directly commands and controls the electronic expansion valves (EEVs) and overall operation of the vapor injection loop.
• Integrated Network:While the HPVCM is the dedicated sub-controller for the physical valves and refrigerant flow of the VIHP, it does not work in isolation. It relies on data inputs and communication shared across other primary vehicle control modules via the CAN bus, including:
  • HVAC Control Module (processes cabin climate requests and ambient/interior sensor data).
  • PCM (Powertrain Control Module).
  • SOBDMC (Secondary On-Board Diagnostic Control Module)

Since the Fathom is going to Zonal architecture with 5 Zones and No CAN Bus (uses Ethernet instead) I wonder if the Heat Pump system was redesigned (skunkworks) from the ground up for the Fathom (Universal EV Platform)?

 

[WXman]

That's a good question. I do know that on the Lightning trucks, there were quite a few reports of HVAC system failures. My 2025 was one of them. The HVAC system had a control module/unit of some kind fail, and that was the only issue I had with the truck.

Also, a point of interest is that several guys who had older Lightning trucks said that the newer ones with heat pumps did not show significant improvements in performance during cold weather. I never drove one of the older ones myself, but my newer one with the heat pump had to work really hard to keep up in the winter. I had to set the auto temp much higher to stay comfy than I do/have in any of my other vehicles. And, the interior would randomly fog up all the time, even with HVAC on. That's not a good thing for safety. The reason that's interesting to me is that Ford went to a great deal of expense to add a heat pump system to the trucks, and if it doesn't really improve things much I wonder if it was worth it.

 

[WXman]

I have actually been looking at used Mach-E cars, and I saw something that jogged my memory. A lot of guys say they've got the interior fogging issue on the Mach-E that also plagues the Lightning. For example, if you set out on a one hour trip, from time to time the interior glass will just randomly fog up. Sometimes it fogs so bad that it hinders visibility. It was one of the things that drove me nuts on the Lighting, but apparently it affects Mach-E owners too.

This is said to happen because of Ford's programming of the HVAC. Whether you manually call for it or not, the software is programmed to switch to recirculate mode periodically. In humid weather this is a recipe for fogging up the interior of the vehicle. Why Ford does this, I have no idea. But a lot of guys have tried to shut that off using tuning software with no success thus far.

Hopefully this issue doesn't carry over into the Fathom as well.

 

[onuiebvbevnulib]

I have actually been looking at used Mach-E cars, and I saw something that jogged my memory. A lot of guys say they've got the interior fogging issue on the Mach-E that also plagues the Lightning. For example, if you set out on a one hour trip, from time to time the interior glass will just randomly fog up. Sometimes it fogs so bad that it hinders visibility. It was one of the things that drove me nuts on the Lighting, but apparently it affects Mach-E owners too.

This is said to happen because of Ford's programming of the HVAC. Whether you manually call for it or not, the software is programmed to switch to recirculate mode periodically. In humid weather this is a recipe for fogging up the interior of the vehicle. Why Ford does this, I have no idea. But a lot of guys have tried to shut that off using tuning software with no success thus far.

Hopefully this issue doesn't carry over into the Fathom as well.

You are completely right. This is a well-documented complaint shared by both Ford Mustang Mach-E and F-150 Lightning owners, especially during freezing or highly humid weather.
The phenomenon comes down to how Ford engineered the cabin climate systems for its early-generation electric vehicles.

Why It Happens
Unlike gas vehicles (ICE) that generate massive amounts of waste heat to warm up and dry out a cabin effortlessly, EVs have to budget every watt of energy carefully.

• Aggressive Air Recirculation: To save battery range, Ford’s automatic climate control logic aggressively defaults to recirculating cabin air rather than pulling in freezing or humid air from the outside. This traps the moisture from your breath and wet shoes/mats, quickly raising the interior dew point.
• The "Auto Mode" Glitch: Many drivers note that the Auto setting fails to balance cabin dehumidification properly. The air coming from the defroster vents can actually blow too cold or shut off the AC compressor prematurely to save power, resulting in instant condensation on the cold windshield glass.
• Camera Blockage: On the Mach-E, this fogging often gets trapped inside the small plastic housing behind the rearview mirror where the front-facing camera sits. When it fogs up, it blocks the camera and causes safety features like BlueCruise or Lane Keep Assist to unexpectedly shut down.

Official Fixes & Updates
Ford has acknowledged this issue. If you are experiencing it, check for the following:

• Technical Service Bulletin (TSB 23-2088): Ford issued a TSB specifically for 2021–2023 Mach-E models exhibiting windshield interior fogging and a lack of heat in freezing temps. The fix requires a dealership to update the HVAC Control Module software via the FDRS scan tool to alter how the car manages airflow and moisture.
• Over-the-Air (OTA) Updates: Make sure your sync and power-up updates are current, as Ford has rolled out background tweaks to the climate software algorithm to keep the AC compressor running longer as a dehumidifier.

Community Workarounds
Until the software logic behaves perfectly, Mach-E and Lightning owners on platforms like the MachEforum and F150 Lightning Forum suggest doing the following:

• Ditch "Auto" When It's Bad: Switch the climate system to manual mode. Manually force the air to blow to the windshield/floor and ensure the A/C button is toggled ON (even when heating) to act as a dehumidifier.
• Force Fresh Air: Check your screen to ensure the recirculation button is turned off so the vehicle pulls in drier outside air.
• Super-Clean the Glass: EVs pull a lot of plastic "off-gas" film onto the glass from the dashboard. Clean the interior glass thoroughly with a 50/50 mix of isopropyl alcohol and water; moisture clings to dust and off-gas film much easier than it does to perfectly clean glass.

Looks like Ford has a few fixes to address the problem (see above).

Hopefully those fixes will be done for the Fathom.

Since I live in Texas I probably won't see any issues but if a freeze does happens here and fogging does happen I will look at the Community Workarounds to help with the issue.

 

[Flash]

I have the fogging issue every once in a while on my Lightning. As mentioned, it's when relative humidity outside is very high.

But I absolutely hated the Tesla Model 3 that I drove and the software overriding the settings that I picked on a long road trip. It drove me crazy enough that I wouldn't own one.

Maybe I am entering old man yelling at clouds territory... But give me manual control of HVAC please.

 

[Snakebitten]

Exactly two years of Mach-E GTPE daily driving.

If Ford could guarantee me that the Fathom will be as well put together as the Mach-E, and be as trouble free as mine was, I would be ecstatic.

I realize the Mach-E never got the fanfare and publicity of some of the other EV's that it competes with, but there's a reason there are so many Mach-E owners that got a second Mach-E after their first. And a few fellas are on their third!

Not a perfect vehicle, admittedly. But I think history will think well of it. And I also think they are going to be on the road for a very long time. It's hard to kill one, without wrecking it.