Another Heater Thread

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04RAM_3

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I looked around a little and don't see what I wanted, so here goes:

The heater in my 04 quit suddenly a few days ago. I was going to put a water pump in it anyway, so while it was out, I flushed out the heater core. It's got great flow and isn't leaking. It switches from defrost to vent to floor perfectly. I crawled under the dash and you can see the actuator moving back and forth like it's supposed to when you turn the knob back and forth from cold to hot to cold again. I noticed that if I put it on defrost it gets really cold. Not near as cold when on vent. So my guess is it's a loose door of some sort in there. Is there a way to get in there and manually move the door so it's always on hot? Then in the spring I could take it apart and put all new stuff in there
 

GTyankee

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the 3rd Generation Dodge Rams & the 4th Gen Rams HVAC are really not that different

Try this to know if each door inside the HVAC Unit actually work

Remove the lower glove compartment door

First locate the Blend Door Actuator
With the Ignition ON in the Accessory position
Reach the HVAC Controls with your hand
Work the controls as you watch the Actuator, you should see a Lever move up & down

NEXT, remove the actuator, should have 2 or 3 screws & an electrical connection holding it in place.
Remove the actuator
If you can stop the actuator when the small lever is in the DOWN position, it makes it a bit easier to reinstall the actuator.

Once the Actuator is unscrewed, the small LEVER should still be fastened to the Door inside the box.
Using your Thumb & Finger, lightly grab the lever & slowly work the lever up & down, as you watched it do, when you watched the actuator move it.

You should feel the weight of the door inside the box, it should feel similar to holding a heavy pen or a 12" ruler by the thumb & finger, you may even HEAR the door inside the box, when it hits the top & bottom positions.

Every one of the actuators & doors should work that way
There will be at least 3 actuators easily found & a 4th one other one that is hidden by the upper glove compartment, that one is not as important, it controls Fresh or Recirculated AIR

I found an image of the thing that i referred to as a Lever

1735789735410.png

The actuator drives this & in side of the box, the Door is driven by the lever

 
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04RAM_3

04RAM_3

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Thank you for the detailed reply. I know what I'll be doing Saturday now. I about froze to death going to work this morning and it isn't even cold yet haha
 
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04RAM_3

04RAM_3

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OK, here's what I did today. I removed the glove box. I can feel the refresh door moving open and closed as it is supposed to. I took the actuator for the climate blend doors off. It works perfectly. I can manually move the climate levers and hear the doors open and close. With the actuator off, if you put the fan on high it blows the doors closed even. It moves from defrost to vent and floor exactly like it's supposed to. I put it back together. Then I parked the truck nose up on a hill. I put my spill-less funnel on the radiator and let it run and run looking for air. Then I took the bleeder off and let it run and run. A tiny bit of air came out, and I mean tiny. Like one or two bubbles. I put it back together and let it run again with the spill-less while I changed the headlights in the Challenger (that's no fun at all). I put the cap back on and ran it up and down the highway. No overheating, but no heat from the heater still. I checked the temperature on the heater hoses and they're within a degree of each other. I'm stumped. Everything seems to work as it should, but no heat
 
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04RAM_3

04RAM_3

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I bought a 12 volt heater for now. We'll see how it goes
 

jws123

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If you moved the door manually and still dont have good heat your heater core is clogged time to replace it not uncommon. You can try using some CLR to flush it first some have luck If you mechanically inclined its not a terrible job to do. You dont have to remove the dash all the way moreso just drop the column and unbolt dash pull it out on pass side let it rest on seat and then remove hvac box it is a big job but sounds way worse ususally takes me a day a ton of youtube vids on it aswell.
 
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04RAM_3

04RAM_3

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The core flows perfectly when I flushed it. However I didn't back flush it. It's simple enough to get to, so I'm going to flush it again Saturday. I'll flush it both directions. While I'm at it, I may as well throw a new thermostat in it. I hope this resolves it. I just about froze to death driving home from work last night lol
 
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04RAM_3

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I've checked everything I can think of. Here's a short of flushing the heater core
Here's a short backflushing it
Here's a short of the climate doors and recirculation door. You can hear the climate doors open and shut. You can see the recirculation door open and close as it's supposed to. I didn't look at the vent doors because that works perfectly
Obviously the core isn't plugged. The doors seem to be functioning as they should. There is no air in the system. Everything seems to be working like it's supposed to, but there's no heat. What am I missing? I'm stumped
 

GTyankee

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I believe that the 3rd Gen Dodge Ram & the 4th Gen Ram HVAC systems are close to the same
The Recirculation Door is up by the upper glove compartment
it supplies Fresh Air or it Recirculates the Cab Air, i close it on cooler days

Then the Blend Door is to the left of the Blower Fan & you said everything there seems to work
every bit of the AIR passes through the Air Conditioning Evaporator
then the BLEND Door directs the air either around the Heater Core, or through it

Then over to the left of the Blend Door, are 2 more actuators & doors, called MODE Doors
Those 2 actuators on a 3rd Gen, are not easy to access
If i had a 3rd Gen, i would be using a Dremel Tool & file

Why the dremel, this video will show it
Go right to about the 1 minute 50 second point to start



this is confusing to me
he calls Mode Doors, Blend Doors

the 2 closest to the steering wheel are MODE DOORS

the one closest to the passengers left knee, is the Blend Door

The one up by the upper glove compartment is the Recirculation Door
 

jws123

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I've checked everything I can think of. Here's a short of flushing the heater core
Here's a short backflushing it
Here's a short of the climate doors and recirculation door. You can hear the climate doors open and shut. You can see the recirculation door open and close as it's supposed to. I didn't look at the vent doors because that works perfectly
Obviously the core isn't plugged. The doors seem to be functioning as they should. There is no air in the system. Everything seems to be working like it's supposed to, but there's no heat. What am I missing? I'm stumped
the core can still be plugged they all flow its the small fins ECT inside that get clogged hence why CLR and flushing only works half the time.
 

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the core can still be plugged they all flow its the small fins ECT inside that get clogged hence why CLR and flushing only works half the time.
^^^^^
This.

Also, if you measure the temperature from input to output on the heater core (in the engine bay) you should see a significant temperature drop.

A laser guided temperature gun is useful here.

If there's no significant temperature drop, there's no heat exchange happening through the heater core.

No heat exchange is either due to no air volume across the core or because of the gunk built up inside, coating the interior.

If the actuators are functional and providing air flow, that leaves one more point of failure, the heater core.

You could try back flushing and or soaking with hot water followed by backflushing.

BTW, IIRC, the warning on CLR is, may damage copper surfaces.

.
 
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04RAM_3

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I ended up pulling the dash and the HVAC. I put all new doors (from Blend Door USA), heater core, and Evap Core since it was apart. The heater works great now!!! My A/C isn't functional yet. I boogered up the connector on a hose so I need to get a new hose. As soon as I do that I'll recharge and be back in business. Looking back, that was a big job, but not all that difficult to do. That being said, I hope I never have to do it again!!
 
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