2003 Ram heater works on one side only

Boomer

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2003 Dodge Ram pickup 1500. 4.7L V8 66000 miles. Std. cab 4wd Single climate zone. Hey guys, this is my Dads Ram pickup. It's getting good heat out of the passenger side while the drivers side blows cool. Both heater hoses are good and hot to the touch. Temp guage is in the middle of C and H and the thermostat is new. Radiator level is good. Is it possible the heater core can be slightly plugged even though both hoses are hot or, would that affect heat on both sides? I'm betting someone here as seen this problem before. Perhaps it's a mode or blend door? I don't want to just throw parts at it because changing the heater core in this truck from what I hear is a real PITA. I'd appreciate any help with this. Thank you in advance for your time.
 

Ford_Dude

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Might want to look at this video http://www.youtube.com/watch?v=KAclL84Qq8E . Apparently its common for the mode doors to fail. The guy gives a lot of info, I am just not sure about the part where he tells you to cut in to the heater box to remove a mode door. Still, between the 3 or so videos he has up he gives a lot of info.

Ford_Dude
 

ironhead

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Actually I`ve done dozens of heater cores, boxes, doors etc in those trucks. You do have to pull the dash, but it`s probably the easiest dash to pull. Granted, like I said I have done lots of them, but I can have one of those dashes completely out in under an hour. Next is the heater box, That can be tricky because the studs that hold it in like to twist out of the box. But other than that, it`s not as bad a job as you would think.
They are well known for broken doors, and that is what yours sounds like to me.

Guy
 

Boomer

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Thanks for the replies guys. I had seen the heater treater videos when I was googling around. Thanks for the link. When googling, i found the same problem at dodgeforum and those guys seem to fix it by either changing the heater core or flushing it. I guess I could try flushing it first and see if that does anything. Won't cost anything except maybe a little antifreeze. Really nothing to lose there. Do I need to make sure I buy the red/orange colored Dodge coolant or does that really matter?

Guy, do you have to drain the A/C system if you pull the dash apart and change the heater core?
 

Ford_Dude

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Hey Boomer,
You can try flushing the core, but typically you get little to no heat if the core is clogged. I believe you have a mode or blend door problem.

Ford_Dude
 

Boomer

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Thanks again Ford dude. Flushing the core makes no sense to me either but, I have seen several different posts from people saying that tixed their vehicle. I was thinking about the door situation but, it seems that if a door wouldn't let any air come in if it was shut. I can't figure out in my mind why it would have heat on one side and cold air on the other. I have been busy and put this off for awhile. Now it's getting cold so it's time to make this more of a priority.

Anyone have an explanation as to why a door being defective would allow heat on one side and cold air on the other?

Also can I mix coolant or do I need to buy coolant from the dealer? Should I just flush and switch to Prestone or peak or something?
 

Boomer

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ironhead said:
Actually I`ve done dozens of heater cores, boxes, doors etc in those trucks. You do have to pull the dash, but it`s probably the easiest dash to pull. Granted, like I said I have done lots of them, but I can have one of those dashes completely out in under an hour. Next is the heater box, That can be tricky because the studs that hold it in like to twist out of the box. But other than that, it`s not as bad a job as you would think.
They are well known for broken doors, and that is what yours sounds like to me.

Guy
Guy, I've never pulled a dash in any vehicle. Are the bolts for the dash pad part on some kind of L bracket buried up high? Maybe you can tell me what door would break and cause heat on one side and, cold air on the other? If you have done so many in this truck, I'm guessing you have seen the heat on one side only problem. The thing I like alot about the heater treater is the metal replacement parts instead of another faulty Dodge plastic part.

I appreciate all info and ideas.
 

brcidd

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Cold on one side and heat on the other- is typical of a dual system where driver's temp door has broken-- the door does not shut off air flow- it meerly routes it through the heater core or not....all air passes through evaporator core, then routed through heater core if temp door is set to heat, if not set to heat, then air is routed around heater core-- so you will always have airflow, just maybe not heated. Your broken door gets slammed in cold air position by the air flow pressure (like a screen door in a windstorm- it gets slammed shut)
 

ironhead

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Yep... What he said!!
To remove the dash, there is a strip up by the windshield that comes off covering the top bolts, then there are bolts along the ends of the dash (I believe 2 on the passenger side, 3 on the drivers side) The bottom bolt on each end, you just loosen, but do not remove, then there are some under the center of the dash. You need to remove the steering column, a-pillar covers, kick panels and whatever you truck has on the center hump of the floor ( center console or just a trim cover) There are electrical connectors at both ends of the dash, and some in the center at the floor, on some models there will be connectors under the a-piller covers.. Once everything is undone, the dash can be rocked pack, pivoting on the 2 bolts that you left in, then lifted off of them and removed from the truck.
That`s it in a nutshell, but a subscription to alldata ( link at the top of the page) will give you a much more detailed procedure.
Guy
 

Boomer

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Thanks guys. This Ram doesn't have the dual temp zone. Could it be that it's equipped with the same door setup from the factory? I figure in this setup the doors would be connected together thus affecting both sides.

Do you have to disconnect the A/C system? The center hump has the handle for the transfer case. It's a 4WD
 

ironhead

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I honestly don`t remember if they use the same box or not, but if you have hot out one side and cold out the other, the problem pretty much has to be in the box.
You won`t need to remove the 4WD shifter, just anything that attaches to the bottom of the dash.
Guy
 

brcidd

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Yes, a/c lines and heater hose need to be disconnected underhood- in order to pull HVAC box out. That is one reason the heater treater fix was invented....
 

Gus

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I know this is a completely different vehicle, but I had a Late model Tahoe, that only had heat on one side.....called TAC.....apparently the new heater core had smaller tubes, and it was possible for the lower section to block up......

They recommended a reverse flush of the core.......crap came out.......and then I had heat on both sides......

I would try the reverse flush first......then if that doesn't work, you check the doors......
 

Boomer

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Gus said:
I know this is a completely different vehicle, but I had a Late model Tahoe, that only had heat on one side.....called TAC.....apparently the new heater core had smaller tubes, and it was possible for the lower section to block up......

They recommended a reverse flush of the core.......crap came out.......and then I had heat on both sides......

I would try the reverse flush first......then if that doesn't work, you check the doors......
Thanks for that info Gus. This gives me reinforcement to try that first. It's worth a shot.

Can you or anyone answer the question about mixing antifreeze or should I get dealer stuff or flush and refill with a readily availabe coolant?
 

billr

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The coolant issue is debatable, some report bad problems using other than OEM coolants while others have had no problem. I think there is general consensus that "extended life" coolant should not be mixed with conventional type coolant.
 
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