HVAC Low airflow and heat - I've researched a lot already!

[greggearhead]

Hello - 1st post.

I have a 2017 Ram 1500 5.7 Hemi, and a newly purchased 2016 Ram 2500 6.4 Hemi. The airflow and heat in the 1500 are great. Can keep up with the coldest or warmest days (Colorado). The 2500 has very low airflow, comparatively, with less on the drivers side, and low heat, also less on the drivers side. Fan works on all settings, and tested it removed - seems to spin well and move lots of air, but that's not measured or anything.

I've researched lots of threads and watched lots of videos. LOTS.

Things I have already done -
1. The 2500 does not have a cabin filter, so I thought that might contribute to the AC evaporator being clogged with dirt and causing the low airflow. I removed the blower fan, and used a camera to look at the evaporator. It is perfectly clean.
2. Verified fan works on all speeds. *Seems* healthy - but...
3. I verified the functioning of the mixing door actuator as well as the door itself flapping and stopping (meaning it isn't broken from the lever/hinge).
4. Verified the recirc door functioning, and the screen from the outside air intake (visible through the door for a split second when it opens/closes) is very clear.
5. Looked under the wiper plastic cover where the outside air intake is. Was clear under the cover (like 2 leaves) and seemed clear in the intakes as well - might camera down them.

Next steps -
1. Measure voltage at the fan on different speeds - should be almost battery voltage on high, is my understanding.
2. See if I can swap the 1500 fan for the 2500 fan - would be a quick easy test/comparison if I can
3. Drill a hole to borescope camera the heater core to make sure it isn't clogged with debris - but my assumption would be if it was, it would flow less on hot and more on cold according to where the mixing door directs airflow. This is not the case.
4. Coolant/heater core flush. I plan on using a flush product and running it for a few days, and then possibly doing it again. I may do the direct heater core flush independent of the cooling system.

I understand the heater core design isn't the best and is prone to clogging internally, but that wouldn't affect airflow, which is very bad compared to the 1500. I don't need it 100% as good as the 1500, but right now, the heat feels like 20% as much and airflow about the same.

Anyone have any tips or tricks or ideas I'm not thinking of? It isn't good enough to drive in the winter cold as it is.

 

[greggearhead]

Oh, forgot to mention - the thermostat appears good, truck heats up relatively quickly and maxes out around 200-212 degrees F usually, and is pretty stable. Coolant level is at max on reservoir.

 

[Rado]

WELCOME to the group !
You have done a lot!
I am no help but PLEASE UPDATE what you do find out !
Hopefully the gear heads chime in

 

[amurp15]

I also have a 2016 2500 with a 6.4, my heater core started leaking so I’m currently replacing both the heater core and the evap core. If you’re not mechanically inclined, I recommend taking it somewhere, it’s a PITA to get the dash out to service this.

I’ll make a ted talk post when I’m 100% done installing about how many design flaws this hvac unit has, but I’ll tailor this to airflow specifically for you. Since there’s no cabin air filter, all the dirt gets in your evap core (and beyond) and clogs it up pretty bad. Get the temp sensor as well, mine was filthy. Also everything is there for you to install a cabin air filter besides the cover. You do have to cut out the plastic they have where it should go, but it’s pretty easy with a plastic cutting wheel and a file.

I attached a picture of my old heater core, old evaporator core, the leak in the housing, the sad excuse for a “filter”, and the hole I cut in the inlet housing for a proper cabin filter. If you have any questions let me know!

 

[Rado]

WOW that is bad !
And WOW what a job :O
And there are still people who say a CAF is not needed
My 2015 I got in 2016 did not have one but did the CAF mod and from the crap it has caught worth the mod 110%
A CAF is cheaper then a coil and evap

 

[greggearhead]

Well, I measured voltage at the fan, 12.36, engine off, all speeds. Must be pulse width modulated speeds?
Anyway, drained coolant, and popped the bottom hose to get as fast a flush as possible, hoping to get as much sediment out as possible. Messy, but works.
Actually got a bunch of crud out. Flushed some water through and put in the flush stuff and water. Ran it and drove and already there is more heat!
Will leave it in for another couple days, flush again, and then put more stuff in and do it again. Such a crappy design to have so many drawbacks.

 

[greggearhead]

Also, ordered new top and bottom radiator hoses. I figure at 185k miles, it's not a bad idea. The top hose clamp I opened to help with burping the system wouldn't tighten back up correctly. So new clamps too.

 

[amurp15]

Dave's Auto Center has a video about casting sand getting inside the heater core from the factory...flushing your system might help a little, but you'll have to replace it if that doesn't work.

 

[mtofell]

Skip straight to #4 on your "next steps" - flush the core. But, skip the additive for a few days. Just tap in and flush.

I'm confused as to how you've done a lot of research but have been messing around with all you have (and plan to do before just flushing the core). I researched online and here with the same issue and all I found was to flush the core directly. And from online and here the success rate to restore heat is well above 90%.

I'm no mechanical wiz and it took me a couple hours and <$50 in parts. I could probably do it again in half the time (either get some good factory clamp pliers or pull the passenger wheel well liner would be my advice). Get a combo air/water nozzle and alternate bursts of each. I could feel my blockage and easily tell when it was freed. Heat came back right away.

Edit/Add - The flow from my 2014 2500 has never been great compared to other vehicles so you might be chasing a problem that isn't there. Maybe go find a used one on a lot to go compare to? Once the heat is back nice and hot the flow is not a problem at all. Defrost is plenty adequate.

 

[greggearhead]

Skip straight to #4 on your "next steps" - flush the core. But, skip the additive for a few days. Just tap in and flush.

I'm confused as to how you've done a lot of research but have been messing around with all you have (and plan to do before just flushing the core). I researched online and here with the same issue and all I found was to flush the core directly. And from online and here the success rate to restore heat is well above 90%.

I'm no mechanical wiz and it took me a couple hours and <$50 in parts. I could probably do it again in half the time (either get some good factory clamp pliers or pull the passenger wheel well liner would be my advice). Get a combo air/water nozzle and alternate bursts of each. I could feel my blockage and easily tell when it was freed. Heat came back right away.

Edit/Add - The flow from my 2014 2500 has never been great compared to other vehicles so you might be chasing a problem that isn't there. Maybe go find a used one on a lot to go compare to? Once the heat is back nice and hot the flow is not a problem at all. Defrost is plenty adequate.

You absolutely aren't wrong, but not knowing 100% if it wasn't a blower or door actuator problem, and how easy those are to check, plus, running a coolant flush is never a bad thing. To that end, just the coolant drain got sediment out. Adding water and running and flushing again got sediment out. Running it with the flush for a few days, then draining got a lot of sediment out. The heat has definitely improved, and my thought process was to run the flush product to help loosen stuff up before flushing the heater core, which I am doing today.

I'll update with results. Thanks for your input.

 

[mtofell]

I'm betting you'll be warm in your truck by tonight

 

[greggearhead]

Flushing the heater core by itself definitely got more sediment out. Not a huge amount compared to what already came out, but definitely got more. I did it both ways, several times - about 10 times, 2 times and switching back and forth 5 times. The heat tonight definitely felt better, but I didn't measure it, but will in the morning.

I added some more flush and refilled with water mainly because I'm waiting on the 2nd new radiator hose, which showed up tonight, so will likely change them both tomorrow and fill with antifreeze for the season. Fingers crossed.

 

[greggearhead]

Well, this morning was 29 deg F out, and I drove the truck and got it up to temp 200-220, and the heater output was 140-150+. Waaaay better than the 75-85 deg previous to any work, and much better than the 120+ deg after the first flush. Will replace the hoses and add antifreeze for the season in the next day or two. The airflow is still not great, but I understand that's just the way it is. Silly when the 1500 blows crazy good from all the front vents.

 

[greggearhead]

Has anyone added a coolant filter to the heater core hoses? I'm strongly considering it, as I suspect there is sediment floating around all the time now. Even if I replaced the heater core, I suspect there would be more sediment that would get in.

 

[joesstripclub]

Has anyone added a coolant filter to the heater core hoses? I'm strongly considering it, as I suspect there is sediment floating around all the time now. Even if I replaced the heater core, I suspect there would be more sediment that would get in.

Casting Sand: 6.4 Hemi HD Coolant Filter

PFA. I’ve noticed a bunch of people dealing with casting sand in their coolant that clogs up their heater core. Seems to be a big enough issue with the penstar that there’s a class action lawsuit over it. I’ve got a continuous flow of casting sand in my 2014 2500 6.4 w/140k miles I’m hoping...

www.ramforum.com

See thread above for some previous discussions on heater core issues and coolant filters.