Temp sensor off, HVAC "cool" when it happens - anyone else?

[ShadowsPapa]

Wondering if anyone else has seen this exact same thing (not general complaints about HVAC, etc - but both of these together, especially the temp sensor)
Multiple times now we have taken off for errands or whatever when it's below 20 degrees out and the display temperature (outside temperature reading) is at least 30 degrees higher.
It happened several weeks ago, just before Christmas and it was 0 and lower outside and the inside reading was at first in the 50s and the more we drove, or the more stops we made, the worse it got. It finally reached 101 on the display when it was hanging around 0 outside. And when that happened, the HVAC didn't warm up the cabin well at all. We had to crank the temperature settings up and then we got cold.

Took it to dealer (after waiting about 3 weeks for an appointment) and they said if it wasn't happening, there wasn't anything they could do. That was Tuesday.
Today is Friday - and it happened again. 4 trips, stops in between, the last stop was back home for 2 hours then back out.
Temps ranged from 55 to 87 on the display, outside it was 18 to 22 degrees.
Last trip I drove into town to eye doctor and realized - it was COLD in that truck.
I took the HVAC out of auto and it jumped to AC mode. I turned off AC and it still didn't kick out warm air. It was a chilly drive back home!

First time - Christmas. 0 degrees out, temps from 70s to 101 on the display. Cold in the truck, my wife said her feet and legs were getting cold and setting the temp to 75 made no difference.

It settled down the next day and worked great - even the HVAC kept us warm when the display worked.

Today - first trip out, it was 18 degrees - this is where it stayed for a while - 50s and 60s -

Today - 22 degrees out, cool air coming out of HVAC. It said as high as upper 80s -

The higher the display read, the less the HVAC kept warm.

 

[ShadowsPapa]

I drove my truck to the dealership this am to chat with my sales guy about the purple Jeep for my wife and figured while I was there I'd make an appointment to have the HVAC and temp sensor checked into.
The service advisor I usually worked with was off today so Scott introduced me to Dan, another service advisor. I swear the guy was some master tech or something.
I knew I'd get blown off, bring it in and if it's still acting up then we'll look at it.
Instead he asked if I had the truck there - yup, and I joked and asked how he liked the 72 degree weather out (it was 12 at the time)
Luckily it's been acting up since last week.
Drove it into their check-in area and believe it or not he connected to the OBD port and went back to his computer and was digging around looking for codes or errors. None (I figured that as I had already looked around in there)
He said yes, everything about the BCM, especially HVAC, is dependent on the ambient temp sensor and the PCM relies on the intake air temperature.
So I was correct - the HVAC sucked because it believed we were roasting inside the truck.
He spend a good 30 minutes with it and said the temp sensor is up behind the grill and wondered- did it only act up with the plow on? Well, it's possible. But then it happens even before the engine warms up, it's wrong when I first start it (he said if it's stopped for more than 4 hours it's supposed to read the current temperature where if it's stopped for less than 4 hours it would take a while to catch up - several minutes of driving over 40 mph. Dang, that service advisor is smart)
Anyway, I told him I had planned on dropping the plow off either today (LOL, right, not with dealing with a new Jeep for my wife) or tomorrow and I'd log everything I saw or observed.
He wondered if there was a dead air space, even a vacuum, caused by the plow.
He shocked me then by saying if we find a pattern there, he can look into moving the sensor so it wouldn't be less likely to be impacted by the snow plow. I can imagine some dealers might say "not our problem, deal with it" or shrug it off. Not him.
When I started the truck the temp said something like 55 degrees and it was barely 11 or 12 plus the temp started going up before the engine was even warm, so it may not be that at all, we'll see, but I'm willing to experiment since he's willing to work with me.

 

[Mr._Bill]

I get that occasionally on my 2020, mostly when it's cold, but not with such a huge temperature gap. It usually corrects itself after a few minutes driving.

 

[wachuko]

And no revised part number for that temp sensor?

 

[ATL_Rubi]

I drove my truck to the dealership this am to chat with my sales guy about the purple Jeep for my wife and figured while I was there I'd make an appointment to have the HVAC and temp sensor checked into.
The service advisor I usually worked with was off today so Scott introduced me to Dan, another service advisor. I swear the guy was some master tech or something.
I knew I'd get blown off, bring it in and if it's still acting up then we'll look at it.
Instead he asked if I had the truck there - yup, and I joked and asked how he liked the 72 degree weather out (it was 12 at the time)
Luckily it's been acting up since last week.
Drove it into their check-in area and believe it or not he connected to the OBD port and went back to his computer and was digging around looking for codes or errors. None (I figured that as I had already looked around in there)
He said yes, everything about the BCM, especially HVAC, is dependent on the ambient temp sensor and the PCM relies on the intake air temperature.
So I was correct - the HVAC sucked because it believed we were roasting inside the truck.
He spend a good 30 minutes with it and said the temp sensor is up behind the grill and wondered- did it only act up with the plow on? Well, it's possible. But then it happens even before the engine warms up, it's wrong when I first start it (he said if it's stopped for more than 4 hours it's supposed to read the current temperature where if it's stopped for less than 4 hours it would take a while to catch up - several minutes of driving over 40 mph. Dang, that service advisor is smart)
Anyway, I told him I had planned on dropping the plow off either today (LOL, right, not with dealing with a new Jeep for my wife) or tomorrow and I'd log everything I saw or observed.
He wondered if there was a dead air space, even a vacuum, caused by the plow.
He shocked me then by saying if we find a pattern there, he can look into moving the sensor so it wouldn't be less likely to be impacted by the snow plow. I can imagine some dealers might say "not our problem, deal with it" or shrug it off. Not him.
When I started the truck the temp said something like 55 degrees and it was barely 11 or 12 plus the temp started going up before the engine was even warm, so it may not be that at all, we'll see, but I'm willing to experiment since he's willing to work with me.

I wonder if something with the plow does cause a vacuum as mentioned, and ends up pulling hotter engine bay air over the sensor... Interesting...

 

[Rusty PW]

I know if I run around for a while. Then park it for 30 minutes or so. Then start it up. Sometimes I notice the outside temp reads a bit higher for a while before it goes back to normal. Figure heat from the motor, radiator is getting the the sensor. My Power Wagon did the same thing.

 

[ShadowsPapa]

I wonder if something with the plow does cause a vacuum as mentioned, and ends up pulling hotter engine bay air over the sensor... Interesting...

It was cool how he handled it. Not accusing, not trying to suggest it was anyone else's problem, not trying to suggest they were washing their hands of it - just trying to brainstorm and figure it out as he was perplexed. He'd found no record of any issues and honestly, the way things lined up he had valid points to consider.
Yeah, the air flow around that plow is crazy - I mean how the filth and slime from the road ends up on the front of the truck and with no other vehicles on the road within a mile, the windshield gets filthy. It's weird. So, I'm going to do everything I can to prove him right or prove it is caused by something else. I'd be wrong to even suggest "not possible". It's very possible.
And the best part - if we, working together, find it is related - he's thinking of ways to get around the problem by maybe moving the sensor.
If nothing else, I'm learning great detail on how that thing does and does not work, and why sometime people see weird stuff even with no plow and no HVAC issues.
And if I do find a connection, it may help others who use plows on Jeeps.

So unless I see snow in the forecast for this week, plow comes off today (just because I prefer to not load the truck up when not necessary anyway)

 

[ShadowsPapa]

Another test. My wife didn't want to get "her Jeep" dirty or put miles on it so we took mine to her MRI this AM. I told her - plow on front, if the plow is causing the temp sensor issues, it's gonna be a danged cold ride across the county! The response - then you'd better warm it up inside fast.
LOL - so across town we go and this time the temps were off but not by a whole lot. I stayed in the 30s, then 40s, and hit a max of 57 by the time we got there (is was 6 degrees out) so we didn't get too cold inside.
On the way back home later the sensor had warmed and it said 67 by the time we drove the 40 minutes back home.
I decided to brave the cold and take the plow off after we got back. It was still reading high when I removed the plow.
A miracle, I decided to take it for a drive up the road after I dropped the plow off the front and watched as the temp slowly dropped down to 7 degrees (it had warmed up a lot outside by that time)
So, it appears the snow plow is creating some warp in the space-time continuum or some black hold vortex and sucking air from the engine compartment forward - even as you drive VERY slowly, like 25 mph. Really?
Even sitting still, that temp sensor reads incorrectly when the plow is on! What the heck? How can that be!
Plow on, temp sensor reads wrong, drive it and it reads even wronger, and the faster you drive the more wronger it gets. Remove plow and drive it a bit and it settles down.

I assume this is the sensor - and it sits so high and so close to the front of the grill - how the heck can that be????

I'm really confused now. I expect something at highway speed, but I'm talking slow enough a bicycle might keep up and it still impacts the readings. Take the plow off, it reads normal.

No, the plow does not connect electrically to anything but the battery and the 12v outlet circuit for the hand held control power. Otherwise, it simply ties to the lights as triggers and is isolated by relays and a big isolation module.

It has to be an air flow issue. When I'm plowing the HVAC will melt plastic parts - it gets hot in there. But it's going sloooow so likely reading normal temps and the plow is down half that time.

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