Need HVAC help.

[SteelWagon88]

I recently bought a 21 Power Wagon and it hasn’t had any heat on the drivers side since the purchase. I’ve read and seen a clogged heater core is typically the issue, but that’s not in my case since I JUST flushed it today… still no improvement. Seeing how this has dual climate control, I’m at a loss since my previous vehicle was a Ram from 1996. Needless to say, I know nothing of my new setup. Any advice would be greatly appreciated here, it’s starting to get cold around my parts.

 

[sherdep]

I recently bought a 21 Power Wagon and it hasn’t had any heat on the drivers side since the purchase. I’ve read and seen a clogged heater core is typically the issue, but that’s not in my case since I JUST flushed it today… still no improvement. Seeing how this has dual climate control, I’m at a loss since my previous vehicle was a Ram from 1996. Needless to say, I know nothing of my new setup. Any advice would be greatly appreciated here, it’s starting to get cold around my parts.

Your not going to get much of a response from this area of the Forum - you should post this question in the General area or Interior or Problems / TSB's area

I take it the truck is not under warranty?
you check Fuses?
Check to see if you have any codes?
I know there are Blend Doors that have actuators that open and close the doors - maybe the actuator is bad or the connection is loose to activate it

 

[Dave01]

So it gives good heat on passenger side, and controls on that side regulate it ok? If you have heat working correctly and blowing hot, that pretty much eliminates heater core/thermostat/coolant level type issues. Blend doors do get stuck, I wouldn't expect it on a '21 but definitely could be the cause. I'd start with this, and I realize you probably already did this but figured I'd mention - "exercise" the heating system with every variation of control you can, multiple times. Go from hot to cold on both sides separately, then put it in "auto" mode and cycle the temp up and down, then back to manual and cycle through the zone settings (feet, feet and defrost, defrost, feet and center, center). Does heat flow from any of the 3 vent zones on the driver's side when you do this?

Sherdep mentioned fuses, I'm not sure there is separate fusing for different zones in the truck, I'm thinking if the blend doors work on passenger side it won't be a fuse issue. Hope this helps!

 

[SteelWagon88]

So it gives good heat on passenger side, and controls on that side regulate it ok? If you have heat working correctly and blowing hot, that pretty much eliminates heater core/thermostat/coolant level type issues. Blend doors do get stuck, I wouldn't expect it on a '21 but definitely could be the cause. I'd start with this, and I realize you probably already did this but figured I'd mention - "exercise" the heating system with every variation of control you can, multiple times. Go from hot to cold on both sides separately, then put it in "auto" mode and cycle the temp up and down, then back to manual and cycle through the zone settings (feet, feet and defrost, defrost, feet and center, center). Does heat flow from any of the 3 vent zones on the driver's side when you do this?

Sherdep mentioned fuses, I'm not sure there is separate fusing for different zones in the truck, I'm thinking if the blend doors work on passenger side it won't be a fuse issue. Hope this helps!

So I did buy a replacement blend door actuator, just in case. But decided to attempt to flush it with CLR and that made somewhat of a difference. Meaning I have heat kind of on the driver side center vent, but not the far left vent on the driver side. But then, the vehicle ended up on an incline and I no longer had heat on the driver side again. So I’m thinking either the heater core got clogged again or it’s completely shot. Then again if the blend doors are stuck, that would explain the intermittent Heat.

 

[SteelWagon88]

I’m curious if anyone on this for him has a simpler way to change the heater core rather than removing the entire heater box assembly. Like, tilt the dash back and loosen the heater box from the firewall, and then swap out the heater core? I’m curious to know if that will be a viable option? Or be able to point me in the direction of a thread on here.

 

[Dave01]

If it was me I'd look elsewhere than the heater core. I really tend to doubt that you get heat on one side, not the other, caused by a clogged core. Maybe someone else will comment, I could be wrong. Also heater core clogging isn't a common problem on 4 year old vehicles.

Is it gas or diesel? Miles? Does engine get up to temp and stay there?

 

[SteelWagon88]

If it was me I'd look elsewhere than the heater core. I really tend to doubt that you get heat on one side, not the other, caused by a clogged core. Maybe someone else will comment, I could be wrong. Also heater core clogging isn't a common problem on 4 year old vehicles.

Is it gas or diesel? Miles? Does engine get up to temp and stay there?

It’s a Power Wagon with the 6.4 HEMI. It has about 162k miles. I’ve combed the internet for a solution and thought possibly someone else would have came across this issue and said something about how they resolved it. All I get is clogged heater core, also I agree a 4 year old vehicle shouldn’t have this issue. This is one of the reasons I bought it, was to retire my 96 Ram so I didn’t have to work on it all the time. But alas, I’m working on a truck I just dropped $32k on not more than 3 weeks ago. I also see that the previous generation was plagued with clogged cores and figured Ram didn’t change much either the HVAC and that the issues might’ve carried over. Maybe I’m wrong, idk? I’m pretty adept in doing my own work on my vehicles, but that’s typically on older stuff. This new fangled stuff has got me stumped.

 

[Dave01]

Maybe you're on the right track then, I just don't know.

If you put the passenger heat on lowest cool setting, driver heat on highest setting, still no heat on driver's side? No difference whether A/C is on or off? Like I said I'd be spinning dials/clicking buttons madly to try to make it work.

 

[SteelWagon88]

Yeah, I’ve done all of that and no change. Driver side vents, still blowing cool air. Regardless of temperature settings, or vent settings. If I remember correctly, even defrost is still cold on the driver side. I just subscribed to an alldata account to look more into it. Trying to see if there any TSBs that relate to my issue, and there aren’t any. I love how I end up with the strangest problems with my vehicles! lol I hate to admit it, but I’m going to have to pull the dash and HVAC unit and replace the core. Once I replace the blend door actuator and it doesn’t change anything, I’ll do the work to swap the core. FML Mopar.

 

[Gear box]

You can test the driver side blend door.If you can get in a warm garage and test it with the A/C system and a temperature gun.If it passes that test it’s your heater core. Our 2019 at work a 3500 cab chassis did this same thing I was able to flush it out to work for 45k then we replaced the core at 100k.The core clogs up on one side by design of it.

 

[Racefumes178]

So I did buy a replacement blend door actuator, just in case. But decided to attempt to flush it with CLR and that made somewhat of a difference. Meaning I have heat kind of on the driver side center vent, but not the far left vent on the driver side. But then, the vehicle ended up on an incline and I no longer had heat on the driver side again. So I’m thinking either the heater core got clogged again or it’s completely shot. Then again if the blend doors are stuck, that would explain the intermittent Heat.

 

[Racefumes178]

I just had this same issue on 2019 Ram ( I have an Auto/truck repair &Towing company) I checke blend door motors with scan tool, they all articulate. I removed the motors and physically made sure the HVAC doors had no obstructions, none. I flushed heater core, but there was on an 8 degree increase, so still cold. I really do not want to have to do a heater core on this truck because it is a bit of a nightmare. So I spent much extra time trying to figure out anything else that it could be to no avail. So I bit the bullet removed the whole dash assembly, evacuated the AC system, drain the coolant, remove the HVAC assembly. Meanwhile, in my head, I’m not too confident that it could be a heater core, because in theory to me, it just didn’t make sense that it wouldn’t blow hot air on the driver side. Also I’ve never done a heater core on a power wagon, although I do own one myself, so I really took my time paying attention to how everything came apart and took pictures and also was very gentle so I didn’t break too many plastic security tabs or other plastic mounting tabs that I couldn’t see. so I installed a new heater core put mostly everything back together, recharge the AC filter, the coolant and sure enough everything worked! I now have 100+ degree heat on both sides, phase floor and defrost and is duels on climate so I was able to fluctuating temperatures. I did cut the old heater open and it’s definitely got some clogging. I’ll send pictures
But now because ihadso many main wiring harnesses apart and battery disconnected,pretty much every warning for Stabilitrak, auto park,traction control lights are all on. I’m using Snap on Zeus to try relearning,resetting everything through Secure Gateway, everything comes back right away. Anyone have any advice..?

 

[johanh13]

I'm having the exact same problem! No heat on drivers side, but everything works correctly on passenger side... argh! I don't want to take the whole dash apart

 

[SteelWagon88]

So I took it to a dealership and come to find out, my cabin temperature sensor was unplugged. I have heat now. Fully functioning. I looked it up, it’s under the knee bolster. Not sure how mine got unplugged, but I don’t care, I’m not freezing anymore! Thanks for the replies folks!!

 

[SteelWagon88]

I just had this same issue on 2019 Ram ( I have an Auto/truck repair &Towing company) I checke blend door motors with scan tool, they all articulate. I removed the motors and physically made sure the HVAC doors had no obstructions, none. I flushed heater core, but there was on an 8 degree increase, so still cold. I really do not want to have to do a heater core on this truck because it is a bit of a nightmare. So I spent much extra time trying to figure out anything else that it could be to no avail. So I bit the bullet removed the whole dash assembly, evacuated the AC system, drain the coolant, remove the HVAC assembly. Meanwhile, in my head, I’m not too confident that it could be a heater core, because in theory to me, it just didn’t make sense that it wouldn’t blow hot air on the driver side. Also I’ve never done a heater core on a power wagon, although I do own one myself, so I really took my time paying attention to how everything came apart and took pictures and also was very gentle so I didn’t break too many plastic security tabs or other plastic mounting tabs that I couldn’t see. so I installed a new heater core put mostly everything back together, recharge the AC filter, the coolant and sure enough everything worked! I now have 100+ degree heat on both sides, phase floor and defrost and is duels on climate so I was able to fluctuating temperatures. I did cut the old heater open and it’s definitely got some clogging. I’ll send pictures
But now because ihadso many main wiring harnesses apart and battery disconnected,pretty much every warning for Stabilitrak, auto park,traction control lights are all on. I’m using Snap on Zeus to try relearning,resetting everything through Secure Gateway, everything comes back right away. Anyone have any advice..?

The only options I see you having are either take it to a dealership and have them do their magic with their witech scan tools, or get alfaOBD and do it yourself (I’ve heard you can do quite a lot with it), or you might get lucky with just unplugging the battery for like a hour and see if the computer will “forget” those issues. Otherwise, I don’t know what else you could do here. I’m new to this new age stuff, my previous daily was a 96 Ram ( I still have it) it was simple to work on, only had 2 computers (1 for ignition spark and timing and the other for transmission). Best of luck to you.

 

[SteelWagon88]

I'm having the exact same problem! No heat on drivers side, but everything works correctly on passenger side... argh! I don't want to take the whole dash apart

Might check your cabin temperature sensor. Apparently it’s important for everything HVAC to function correctly. As I said before, the dealership found mine unplugged and once they plugged it back in, my heat worked fine afterwards. I did try to back flush my heater core 3 times, each time using a different method. That might’ve helped too. But id check that sensor, it should be under the steering column somewhere. I’m not sure what it looks like or its exact location. I could look it up on alldata and possibly get a better idea for you. At any rate if the sensor is plugged in for you and you tried flushing the core and still didn’t have heat, then maybe a actuator is bad, a blend door broken, or the core is shot and needs replaced. Which I have instructions on how to do it from alldata.