Constantly adjusting heat

[JimmyZ]

I haven’t been told about a factory fix but I found if I turn it down to LO and then back to 68 it blows colder (for a little while).

 

[Ruffone]

I have figured out that if you put on Max A/C it takes it out of heat mode. Then you adjust it to the temperature you want following that step and the cooling stays on your desired temperature. Once you adjust the temperature, the system automatically takes it out of Max A/C mode. For some reason just putting it on normal A/C, like mentioned above, it refuses to leave heat/defrost mode.

 

[jack2500]

I just took delivery of a new 2019 Limited. I have discovered that with the a/c on "auto" when the inside temp reaches the preset number, the blower fans shut down. No air coming through the vents. Lower the temp setting and the system starts blowing air again. Every vehicle I have ever owned continued to blow air through the vents continuously and the compressor cycled on and off to maintain the set temperature. I sure hope that there is a fix for this and that this is not the design of the truck.

 

[Deleted member 80]

Welcome to Dodge HVAC. My '05 A/C was marginal, and would get warm in slow driving, as they didn't run the fan to cool the condenser. I was very fortunate to have avoided the dreaded blend door failures that ran rampant in the 3rd Gen trucks. Just google "heater treater". My wife's '06 Charger had the hot air infiltration problem pretty bad. My '15 2500 was a definite improvement in all aspects. Now, this '19 pretty much sucks. Hot air infiltrates and fights the A/C, even on Max Air it can barely keep up on a hot AZ day, it goes through some wild temperature fluctuations, and once in a while will blow scalding hot air out the driver's side vents. On Max Air with fan on HIGH(7) the A/C struggles to get down to 50, and rarely will get below that. On a cool morning, I like to run with the A/C off and just run the fan like selecting "vent" in the old days. With the temp selector set to LO enough hot air infiltrates the plenum that it will add about 15 degrees to the outside air. I run an A/C thermometer in my center vent, to the left of the radio just for this purpose. It is amazing to me that after all this time they still haven't figured out how to make an HVAC system for these trucks. As much as I don't like Ferd, and I stopped buying them because of major issues, I never owned a Ford that you couldn't "hang beef" in. They would put frost on the windows.

 

[g00fy]

What ever came of this? I retrofitted a 12" UAX into my tradesman with single zone climate control, added a cabin temperature sensor, and the ATC solar sensor, and I'm having a very similar issue. However since i have single zone blower system, instead of getting blazing hot air from just the driver side vents i get it from ALL vents and can't get cool air until i knock the system all the way down to low.

Recently AlfaOBD released an update to add support for the 2019+ Climate control system so i was able to go in and actually see what the system was doing to regulate the cabin temperature. I found something interesting, and I don't know if it's got to do with the fact that i retrofitted the system in, or if maybe there's a software glitch in the truck.

When I checked the real time data of the following things I found that the DRIVER SIDE TEMPERATURE SET POINT WAS BLANK no value, and the CABIN TEMPERATURE SENSOR, which should show the live actual air temperature in the cabin, was actually showing the Driver side Temperature setting.

So for example, it's 55 degrees and sunny OUTSIDE and i have the temperature in the cab set to 70, but it's starting to get too hot in the cab for me, like most of you guys have been having issues with. So I turn the driver side temperature to 66* F, now according to the computer the cabin temperature sensor value is now showing 66*F. So the truck thinks it is now 66* in the cabin, and it throws MORE heat at me instead of switching to cooler air to bring the temperature down to 66*. This behavior continues as i push the temperature further down until i get to LO, then it FINALLY starts throwing cool air at me. Here's some pictures to kinda help illustrate what's going on.

Here's what the truck is showing when i have the temperature set to 72*F (21*C Sorry AlfaOBD only does Celsius)


Here's what the truck is seeing when i have the heat set to HI


And Finally here's what the truck is seeing when i set the Temperature to LO:

 

[g00fy]

If anybody else with a factory UAX system can log the same parameters with AlfaOBD it'd be interesting to see if the logs show the same messed up data as my truck.

 

[RainDesert]

Welcome to Dodge HVAC. My '05 A/C was marginal, and would get warm in slow driving, as they didn't run the fan to cool the condenser. I was very fortunate to have avoided the dreaded blend door failures that ran rampant in the 3rd Gen trucks. Just google "heater treater". My wife's '06 Charger had the hot air infiltration problem pretty bad. My '15 2500 was a definite improvement in all aspects. Now, this '19 pretty much sucks. Hot air infiltrates and fights the A/C, even on Max Air it can barely keep up on a hot AZ day, it goes through some wild temperature fluctuations, and once in a while will blow scalding hot air out the driver's side vents. On Max Air with fan on HIGH(7) the A/C struggles to get down to 50, and rarely will get below that. On a cool morning, I like to run with the A/C off and just run the fan like selecting "vent" in the old days. With the temp selector set to LO enough hot air infiltrates the plenum that it will add about 15 degrees to the outside air. I run an A/C thermometer in my center vent, to the left of the radio just for this purpose. It is amazing to me that after all this time they still haven't figured out how to make an HVAC system for these trucks. As much as I don't like Ferd, and I stopped buying them because of major issues, I never owned a Ford that you couldn't "hang beef" in. They would put frost on the windows.

You describe my last 2019 2500 and current 2020 1500. 2 trucks in a row is not a fluke, the current system is a poor design.

 

[g00fy]

You describe my last 2019 2500 and current 2020 1500. 2 trucks in a row is not a fluke, the current system is a poor design.

My 2015 climate control worked awesome, I never had to touch it, idk why ram went and changed it to this new system.

 

[@JC]

It must be fixed in the 2020, my wife complains about how cold the AC is all the time when I'm driving and has a blanket by her feet she can pull up to stay comfortable.

 

[IronByron]

It must be fixed in the 2020, my wife complains about how cold the AC is all the time when I'm driving and has a blanket by her feet she can pull up to stay comfortable.

Same with my 2019, I have had it almost a year and don’t think I have ever touched or adjusted the temp. It’s been on auto always and seems to work perfectly. Never been too hot, never been too cold (I do believe the females in my clan have complained about being too cold in the AC).

 

[Cummins4ever]

my 2014 longhorn climate control and manual climate controls worked amazing, flawless id say. i always left it on like 72* synced and never touched it. My 2019 is a total pain in the rear when it comes to this. I literally adjust the temps non stop, you'll have 72* set and it will be blowing like its either set at 85 or 65, just depends on how the truck feels from one key start to the next. Id throw it in auto mode but it only blows out of defrost in auto mode which im skeptical if that is even correct cause my 14 blew out any vent you selected while in auto. If i change it to front dash and feet, it will disable "auto"

also i had it on "auto" when on a 12 hour road trip (never shut the truck off once) we all noticed it just randomly went from blowing on "auto" out of the defrost to coming out the feet and front dash vents after about 5 hours on the road.....very odd like a blend door is messed up or something. I never touched anything, it just switched on its own. There is no control over the heat and cool unless its in auto and you just let it blow out of the defrost. if your in manual all you do is change the temps by the minute and one degree will change it to either really hot or really cold.

 

[g00fy]

I think every time the truck is started, it monitors the cabin temperature continuously throughout the drive and adjusts the temperature accordingly. For example, I get in the truck, it's 58 degrees out, i have the temp set at 70, so the truck thinks the cabin temperature is 70, and it knows the outside temp is 58. So the truck blows luke warm air to maintain 70, but of course you start driving the suns out, and that luke warm air quickly makes it too warm in the truck, i change the temp to 68, now the truck thinks the cabin temperature has just dropped from 70 to 68, so it starts blowing MORE heat, so i turn the temp down to 64, truck thinks the cabin temperature just went from 68 to 64, the truck thinks is getting much colder, so it blows pretty much maximum heat at me.

I force the the temperature to LO, according to the logs, the truck is now seeing 0 degrees in the cabin, however some other piece of programming sees the LO setting and overrides the climate control logic and gives me cold air. I leave it for a minute, then slowly start working the temp back up, now i set the temp back to 64, so the truck sees the in cabin temperature spike from 0 to 64, and now gives me cool air because it sees the temperature is quickly rising, and continues to give me cool air up to 68 - 70 degrees depending on the outside temperature.

What i find super curious is the vent door control & fan speed seem to work correctly, if i turn the temperature setting down it changes the air flow to the dash vents as it's supposed to and it increases fan speed, but the temperature control gives me heat instead of cool air. And i've seen on the few hot days we've had so far, if i push the temperature UP, the vent control changes to foot vents and defroster and the fan speed goes up, but it continues to give me cool air.

It's almost like the Uconnect has control of the Vent Position and Fan speed, but the Climate module is doing it's own thing with the temperature based on the wonky data it's seeing from the false cabin sensor data.

 

[Deleted member 80]

Lots of strange behavior. Sometimes on a cold start, not cold ambient, but first start of the day, if I set it to Auto it will blast the fan and blow cold(well, as cold as this thing gets)air, actually more than necessary at this point. This aggravates my wife. On the flip side, go somewhere while it's hot out, and the truck heat soaks a while, come out and start up on Auto with temp set to LO, and it will seemingly be in a stupor, not reacting to the cab that is like a broiler. In these circumstances my wife's old Acura will automatically turn on Max Air, but this thing won't do that. Minutes go by, and it is still not doing much to cool the cab... now I am pizzed. There are instances where I will turn the system off, and then turn it back on, and it will wake from its slumber and start blowing cold air, and sometimes it just lazily puffs while I am boiling. Whether it's hardware, or programming, this HVAC needs some serious improvement.

 

[2019_Ram]

What ever came of this? I retrofitted a 12" UAX into my tradesman with single zone climate control, added a cabin temperature sensor, and the ATC solar sensor, and I'm having a very similar issue. However since i have single zone blower system, instead of getting blazing hot air from just the driver side vents i get it from ALL vents and can't get cool air until i knock the system all the way down to low.

Recently AlfaOBD released an update to add support for the 2019+ Climate control system so i was able to go in and actually see what the system was doing to regulate the cabin temperature. I found something interesting, and I don't know if it's got to do with the fact that i retrofitted the system in, or if maybe there's a software glitch in the truck.

When I checked the real time data of the following things I found that the DRIVER SIDE TEMPERATURE SET POINT WAS BLANK no value, and the CABIN TEMPERATURE SENSOR, which should show the live actual air temperature in the cabin, was actually showing the Driver side Temperature setting.

So for example, it's 55 degrees and sunny OUTSIDE and i have the temperature in the cab set to 70, but it's starting to get too hot in the cab for me, like most of you guys have been having issues with. So I turn the driver side temperature to 66* F, now according to the computer the cabin temperature sensor value is now showing 66*F. So the truck thinks it is now 66* in the cabin, and it throws MORE heat at me instead of switching to cooler air to bring the temperature down to 66*. This behavior continues as i push the temperature further down until i get to LO, then it FINALLY starts throwing cool air at me. Here's some pictures to kinda help illustrate what's going on.

Here's what the truck is showing when i have the temperature set to 72*F (21*C Sorry AlfaOBD only does Celsius)
View attachment 4503

Here's what the truck is seeing when i have the heat set to HI
View attachment 4504

And Finally here's what the truck is seeing when i set the Temperature to LO:
View attachment 4505

So I did some looking on my 2019 Longhorn 2500 Diesel today. It came from the factory with the 12.1" screen. I am seeing the same thing you are. This data was pulled from AlfaOBD on Android.

"Cabin Temperature Sensor" does not appear to be reading the cabin temperature, but rather the "ATC Set-Point Temperature - LEFT". As you change the set temperature in the cabin, this value changes.
"ATC Set-Point Temperature - LEFT" does not show any value, it remains blank. Nothing happens as you change the set temperature in the cabin.
"ATC Set-Point Temperature - Right" seems to show the correct value. As the set temperature in the cabin is set, it changes.

I believe AlfaOBD is incorrectly interpreting the "Cabin Temperature Sensor" and "ATC Set-Point Temperature - LEFT", but I have no other reading software that will let me confirm this hypothesis.

I would love to have access to a Witech scanner and be able to actually see values that Ram thinks the computer is seeing, instead of hearing "Passed the cool-down test" and "Working as designed" from the dealer. "Working as designed" does nothing for me when I am sweating through my shirt before the cab gets to anything remotely resembling cool...

 

[thestuarts]

If anybody else with a factory UAX system can log the same parameters with AlfaOBD it'd be interesting to see if the logs show the same messed up data as my truck.

@g00fy @Jimmy07 I was able to exactly reproduce the behavior g00fy reported with my factory-installed, dual-zone system.

The DRIVER SIDE TEMPERATURE SET POINT was blank, and the CABIN TEMPERATURE SENSOR was showing the Driver passenger side Temperature setting. Who can we reach out to with this amazing observation?

This is when the temperature was set to 71 degrees.




The temperature set to HI.



The temperature set to LO.

 

[thestuarts]

I believe AlfaOBD is incorrectly interpreting the "Cabin Temperature Sensor" and "ATC Set-Point Temperature - LEFT", but I have no other reading software that will let me confirm this hypothesis.

That is a possibility, but I am observing the exact same behavior g00fy reported which can be explained by the sensors being wired or programmed incorrectly.

For example, I get in the truck, it's 58 degrees out, i have the temp set at 70, so the truck thinks the cabin temperature is 70, and it knows the outside temp is 58. So the truck blows luke warm air to maintain 70, but of course you start driving the suns out, and that luke warm air quickly makes it too warm in the truck, i change the temp to 68, now the truck thinks the cabin temperature has just dropped from 70 to 68, so it starts blowing MORE heat, so i turn the temp down to 64, truck thinks the cabin temperature just went from 68 to 64, the truck thinks is getting much colder, so it blows pretty much maximum heat at me.

I force the the temperature to LO, according to the logs, the truck is now seeing 0 degrees in the cabin, however some other piece of programming sees the LO setting and overrides the climate control logic and gives me cold air. I leave it for a minute, then slowly start working the temp back up, now i set the temp back to 64, so the truck sees the in cabin temperature spike from 0 to 64, and now gives me cool air because it sees the temperature is quickly rising, and continues to give me cool air up to 68 - 70 degrees depending on the outside temperature.

 

[Burton12387]

@g00fy @Jimmy07 I was able to exactly reproduce the behavior g00fy reported with my factory-installed, dual-zone system.

The DRIVER SIDE TEMPERATURE SET POINT was blank, and the CABIN TEMPERATURE SENSOR was showing the Driver side Temperature setting. Who can we reach out to with this amazing observation?

This is when the temperature was set to 71 degrees.

View attachment 5034


The temperature set to HI.

View attachment 5035

The temperature set to LO.

View attachment 5036

This much better explains my problem I’m having than the idea of bad refrigerant or a blend door issue. As I’m able to see 46 degrees out of my passenger vent, 55 degrees out of my driver vent, but in “auto” mode, i can never get the cab temp to get within 8-10 degrees of the set point. I can only cool the cab by setting it to “lo” with a fan speed of 4 or so and just let it go forever. And in “lo” I see 46 degrees passenger vent, 55 degrees driver. So the system IS capable of 46 degrees vent temps. (86 degrees out).

I have an appt Tuesday, maybe I’ll print out your results, and instead of blaming/attacking the vent temps, try to direct/complain more about about “auto” mode being screwed up and how it never controls the cab temp correctly.

The optimistic side of this is maybe once the right person gets involved, this is as simple of a fix as a software update and possibly a new sensor?


Sent from my iPhone using Tapatalk

 

[jbncccb]

Can we send this info to FAC to get an update in the works. Excellent troubleshooting guys.

Sent from my ONEPLUS A6013 using Tapatalk

 

[g00fy]

Of all the irrelevant aftermarket modification threads @RamCares loves to chime in on, and here's an actual factory defect and they're nowhere to be found.

 

[Gondul]

Of all the irrelevant aftermarket modification threads @RamCares loves to chime in on, and here's an actual factory defect and they're nowhere to be found.

They replied to this very thread on page 1...