Passenger Air Warmer than Driver despite being set Lower

[isthismyusername]

While driving I noticed that my passenger air temperature coming out of the vents was significantly warmer than my driver side despite my passenger side being set to 65 while the driver side was 70. I messed around with the climate settings a bit and found while the climate control was Off Dual Zone, Auto control On, and the temperature being set to the exact same on both sides the driver side feels 5-10 degrees cooler than whatever is coming out of the passenger side. When set to 70 in Auto, Dual Off The Driver side is blowing cold air, the Passenger is blowing heat. Does anyone have any idea what may be causing this? Fuses I could check or anything? I believe the driver side is the one that is screwed up. The air coming out of the vents feels freezing cold even with it set to mid 70s. I tried looking on the threads but couldn't find anything, thanks!

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[DukeCanBuildit]

Tough break Mike. Scroll to the bottom of this thread and you’ll find similar threads to this one…

Good luck.

 

[airline tech]

Copy and Paste from Previous Threads:

To highlight operation of the doors.
In Heat operation they open
In AC Operation they close

These PID's are from my Autel Scanner, I do not believe Forscan will display these Pids
Yet - Anyway

Notes: For T/Shoot
Mode Door Position: (Normal Readings as Follows)
Defrost = 100%
Panel = 0%
Floor = 50%
Blend - Panel/Floor = 25%

Left / Right Blend Door (This is the Temp Actuator/ Door) Position, this will check max travel open and closed.
Any selected temp in between the (percent) will vary.
Hi (Heat) = 0%
Lo (Cold) = 100%

Left Discharge Panel Temp / Left Discharge Floor Temp
These temps will vary but should be close to each other, if mode is placed in Blend (Panel/Floor) if you wait about 5 minutes or so the temps should be near equal.

External Amb Temp - Should match OAT Temp, using your phone etc.

Internal Amb Temp - This is the Temp/Humidity Sensor, this reading will read high and or low, if just sitting still as the heat/cold air is rising up from the floor vents through the dash.


and this:


Did small ops check just for curiosity.
OAT = 5 Deg F
Dual Auto Set to 72 Deg

Initial start - Auto Mode moved to Defrost Vents
After warmed up - Auto Mode moved to the Floor, with a small amount still being pushed out through the defrost vents and the 2 (side of the dash) demisters.

Strong Air Flow both Floor Vents and with Digital Thermometer:
Measured 110 Deg at Driver's Floor by brake pedal.
Measured 120 Deg at Passenger Floor

The reason for the passenger side to be warmer is due to the way the system operates.
The main feedback temperature reading is at the Temp Humidity Sensor, it will use whatever means it takes to get a balanced FULL CABIN temperature to whatever you have selected (in my case 72 deg)

Note: You will get different results Sitting at Idle vs Driving, as with driving you have the forced airflow from the Air Inlet Door to help circulate the air.
Sitting at idle, the heat will just rise on the driver's side, it will rise up to the Temp Humidity Sensor and provide a Hotter result.

Measured 73 Deg at the (Humidity Temp Sensor) Inlet by the Ignition Switch
This is the small little vent beside the Push Button Start Switch

Now mine is a 2022, so as far as I know I have the upgraded HVAC Box.
But I have been trying to understand why some complain about low airflow or cold feet.
Possibly the Older HVAC box design??

In any case, one should be able to set the heat to HI and blower to Max Speed and set the mode to the Floor and you should be getting a strong airflow on both sides and have heat at about 160 Degrees or higher- IF all is working normally and engine temp is about 195 (Normal Operating Temp)

This test forces the system to operate with Temp Doors (Full Open) so you are getting all air off of the Heater Core)
This would be an alternate way to test if you do not have the ability to use a scanner capable of displaying the proper PID's.

As I have stated before, my feet get HOT, and I find myself dialing the Temp Down to around 65 or so to get comfortable feet or I move it to Defrost Only



So, you are possibly correct.
The Driver's Side - Temperature Actuator appears to be not functioning correctly and you can use one of the methods above to help troubleshoot it.
A scanner capable of seeing actual position is best as you can see the actuator movement. (0-100%)

 

[btsmith52]

I have a similar issue to this in my 2022, and have so far decided not to haul it to the dealer, simply because it is difficult to duplicate. Overall, the truck cabin heats up and cools down as needed. If you manually manipulate the HVAC, there is nothing mechanically wrong. Both side can make cold and hot air and can move the air too all of the appropriate locations on demand.

What appears to be happening is that the driver side measures air to be warmer than the drivers side by at least a few degrees. When it's very cold or very hot, the issue doesn't appear. When the temperature is moderate, or when I've been driving a long time, the issue appears. The drivers side tends to blow cooler air through the dash vents, and the passenger's side tends to not blow air through the dash but to the floor, and the air tends to be warmer. I can make the sides balance by setting the passenger side to a few degrees cooler (2-3) than the drivers side.

It's difficult to duplicate on demand, and I really don't want the dealer to tear the dash open of my relatively rattle free truck . . . . . Still wish there was a solution to the mildly annoying problem of an otherwise great truck.

 

[isthismyusername]

Figured id update this for anyone having this issue in the future. I just received a message from the dealership and I was told that they have gotten approval to replace my "evaporator case" under warranty. My truck is a Gold Certified vehicle, managed to get back from my trip with 422 miles left on the warranty. Hopefully when I get it back the issue will be resolved!

 

[JasonTremor]

The 2021 I had had a similar temperature imbalance issue. My testing results were here: https://www.ranger5g.com/forum/thre...eat-to-work-in-auto-setting.26806/post-620381

I never pursued it with the dealer before I traded it in. Sounds like your dealer is taking care of you.

 

[airline tech]

Figured id update this for anyone having this issue in the future. I just received a message from the dealership and I was told that they have gotten approval to replace my "evaporator case" under warranty. My truck is a Gold Certified vehicle, managed to get back from my trip with 422 miles left on the warranty. Hopefully when I get it back the issue will be resolved!

Good News

The latest SSM only replaces the actual problem part vs the whole assembly as above.

Still labor intensive for access though.

 

[btsmith52]

I took mine to the dealer, after all. They replaced the entire HVAC in dash air box, and it didn't fix the problem. I believe what they replaced was essentially the same as in the 2019 TSB. Just my luck. I suspect either a temperature sensor or whatever module is controlling the thing.

 

[airline tech]

I took mine to the dealer, after all. They replaced the entire HVAC in dash air box, and it didn't fix the problem. I believe what they replaced was essentially the same as in the 2019 TSB. Just my luck. I suspect either a temperature sensor or whatever module is controlling the thing.

I would think a temp sensor as well.
It has 4
Drivers Panel Temp - Discharge Temp in the Duct (Provides feedback to the FCIM for output temp)
Drivers Foot Temp - Discharge Temp in the Duct (Provides feedback to the FCIM for output temp)

Humidity Temp Sensor - In Cab Temp & Humidity Reading. This is a feedback to the FCIM for actual in cabin temp, now in AUTO mode, this sensor will calculate an average overall temp based on what you have selected.

So, this means for the overall cabin temp to be let's say 72 deg, the system will adjust the passenger side about 10 degrees warmer or cooler to get the overall cabin temp to stay at 72 degrees. As measured at the Cabin (Humidity Temp Sensor) which is located above your right knee by the ignition switch. (small little vent)

Once, it has reached its calculated temp reading, it equalizes the drivers and passengers temp output. (I hope this makes sense) Think (Overall Cabin) not just per side (It's an AVERAGE - NOT EXACT)

Another way to put it (It will mix the air to get the cabin temp to the selected value) this includes pushing hotter or colder air into the passenger side which will push and circulate into the cabin and mix with the driver's side output air.

The above 3 - measure and control the temperature doors from the (selected temp on the Sync Screen) but the actual controlling module is the FCIM (Which is the panel the physical buttons are on)

Evap Core Temp - This is used to Turn Off the AC Compressor when the Evap Core reaches 35 degrees. (keeps it from icing up)

On a side note, a couple weeks ago a member had a similar issue with AC, Cold Air
He found a leak in the system and recharged it, works normally as of his last post.

I am somewhat confused by the Temp Output, being different (between drivers and passenger) with a Low Freon charge.
I think it has to do with PRIORITY programming in the FCIM, Prioritizing the Driver's side output and keeping the Passenger Temp door in a somewhat deactivated failure mode state, no matter what the actual temp is selected to on the passenger side.
This would pull the maximum cold air from the Evap Core.
The driver's side cannot be driven to the selected COLD temp and the passenger side is the follower, so it disables itself until the driver's side can be met.

Another Confusing Point:

I am trying to understand how the system can have Panel Air on the Driver's side and Floor Air on the passenger side. There is only (1) mode door actuator.
Hopefully when (quangdog) replaces his and posts it opened up, we can see if it is actually separate doors being driven by (1) actuator.

 

[airline tech]

I have never really paid attention to airflow , difference between drivers and passenger, and the only thing I can possibly see is that the passenger air temp door can position itself to block airflow , say from the vents on passenger side while the drivers side is blowing through the vents.
Giving you the feeling that is may be routed to the floor as I just tested mine with outside temp 60 degrees and selected temp (dual) at 70- have air from drivers (panel) and no airflow on any passenger vents - dial up the passenger temp and airflow moves to the floor , dial down the passenger temp and airflow moves to passenger (panel) vents.
So my conclusion is that we only have (1) mode door to direct airflow, but the temperature door has the capability to block that airflow if needed to get the overall cabin temp as read by the humidity temp sensor to the selected temp.
So it has the ability to adjust temp (hot/cold) plus block off airflow, the airflow that is blocked depends on what airflow mode the system is in.
And the mode doors themselves are not individually operating separately.

 

[btsmith52]

Took mine back to the dealer this morning because the problem persists. Tech said the only thing left to replace is the FCIM, so I think that's the path they are going down.

 

[btsmith52]

Ford's final answer on this was . . . . and I quote . . . . "likely an undesirable characteristic which is a result of the way the vehicle was engineered and manufactured". Wow . . . . that must have been hard to admit. Suckage is engineered into the product . . .

 

[alcohenusa]

Ford's final answer on this was . . . . and I quote . . . . "likely an undesirable characteristic which is a result of the way the vehicle was engineered and manufactured". Wow . . . . that must have been hard to admit. Suckage is engineered into the product . . .

That’s their standard answer when they know something is not right but they either don’t know how to fix it or they choose not to fix it.

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