heating issues

[rwcllc]

I have a 2018 ram 3500 tradesman that is blowing cold air on the drivers side and hot air on the passengers side. Anyone else have these issues?

 

[johanh13]

I have that same issue on my 2019. So far no luck finding out what it is. I have tried the calibration, which I get no response. Other than that, it seems I need to tear into the dash, it's likely a blend door motor....

 

[johnmyster]

Heater core clogs on bottom (drivers) first.

It wouldn't be winter without daily posts regarding clogged heater cores and battery tenders.

Post in thread 'Poor heat output'

Dec 18, 2025

I’ve got a 21 powerwagon. I just noticed the air conditioning heat is pretty poor for the first use in the winter. Anyone else had this issue? Fix?

Air conditioning heat? You mean the heat… the blend door may be stuck or check your cabin air filter

• H3LZSN1P3R

 

[RiverRunner1775]

I started having this issue a few weeks ago on a 21 6.4, 83K miles. Coincidentally a coworker with an 18 6.4 started having the same issue before me. He flushed his heater core with some success but he hasn’t completely got it fixed. I went and bought a Lisle heater core flush tool that uses compressed air and water and set the PSI low and flushed the core. It fixed my issue. But I went further.

I bought all the parts to install a WIX coolant filter inline from the water pump supply to the heater core. I got it installed yesterday and after I ran it a bit and got the air burped out from breaking the system open all was well. Drive it to town earlier today and I had good heat until I didn’t. I think the filter is already stopped up. If I drive hard and get the rpms up it makes a little heat. Grabbed another filter while I was in town. Once the engine cools I’m gonna swap it and cut open the old filter.

 

[RiverRunner1775]

I drained the coolant, flushed best I could and installed a new filter and Mopar coolant. Coolant shouldn’t look like this after 83K miles. Heat is back working. But I need to grab another filter, I’m sure it’s gonna stop up again. Might as well buy a case.

 

[RiverRunner1775]

Here’s the filter cut open and pressed on fresh paper towels. 27 micron might be a bit much. Very fine rust like stuff. I think there are 50 micron ones available. I only ran the filter about 60 miles.

 

[RiverRunner1775]

Trial and error, this filter probably isn’t the best option for the way I have this setup. I don’t believe it has enough flow for a heater core setup. It’s designed more as a tap filter with a low flow rate, hence 27 micron. I’m not even sure 50 micron would be open enough. Actually I stand semi corrected, all filters have an internal bypass. So if the pressure feeding the filter is high/the filter clogs fluid will bypass the media. Of course the bypass pressure varies by filter. But I do know the Wix 24070, 27 micron was stopped up and I was only getting smidge of coolant flow with rpm creating pump pressure. I replaced it with a 24070 but I think I’m going to order some Donaldson P554685 50 micron.

Or I may have to ditch it all together if it constantly stops up. But the drain and fill was definitely needed.

 

[johnmyster]

Or I may have to ditch it all together if it constantly stops up. But the drain and fill was definitely needed.

Sounds like it would waste lots of filters trying to clean/save that coolant. Have you considered a flush cycle with a cooling system cleaner? Prestone citric acid cleaner, Fleetguard Restore or Restore+, etc. Even a drain and fill is going to leave lots of residue in the low points of the system. I'd want to run lots of garden hose water through the radiator and block, and then blow down with compressed air, over and over again.

 

[RiverRunner1775]

Sounds like it would waste lots of filters trying to clean/save that coolant. Have you considered a flush cycle with a cooling system cleaner? Prestone citric acid cleaner, Fleetguard Restore or Restore+, etc. Even a drain and fill is going to leave lots of residue in the low points of the system. I'd want to run lots of garden hose water through the radiator and block, and then blow down with compressed air, over and over again.

Flushed it after the first filter. Already had the stuff. Just installed the filter first as a trial. I’ve driven it twice since the coolant flush and heat is good. OAT coolant is junk. We have a 4Runner with POAT with 200K miles and the coolant tank looks new, zero crud. The coolant has only been changed once at 150K.