Heater problems

Tiny
DODGE1
  • MEMBER
  • 2007 DODGE RAM
  • V8
  • 4WD
  • AUTOMATIC
  • 30,000 MILES
I have a 2007 dodge ram 1500 4x4 4.7 hemi. The heater will blow hot and all at once start blowing cold. Then the heat gauge starts to go up and truck tries to overheat.
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Wednesday, December 8th, 2010 AT 6:18 PM

22 Replies

Tiny
DOCFIXIT
  • EXPERT
Hello,

It sounds like you have a blown head gasket which filled the heater core with exhaust gases which makes the heater stop working here are two guides to help us get started.

https://www.2carpros.com/articles/car-heater-not-working

and

https://www.2carpros.com/articles/head-gasket-blown-test

Please run down these guides and report back.
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Wednesday, December 8th, 2010 AT 6:25 PM
Tiny
HLACEFIELD
  • MEMBER
I had the same problem and had to replace the blend door actuator.
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Monday, January 7th, 2019 AT 6:53 PM
Tiny
CCORCHADO@LIVE.COM
  • MEMBER
  • 2007 DODGE RAM
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 162,000 MILES
It will not give heat especially when is running. Already replaced water pump, flush heater coil and replaced thermostat
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Friday, November 27th, 2020 AT 11:01 AM (Merged)
Tiny
STEVE W.
  • EXPERT
Check that the clutch on the engine fan is working. If it is malfunctioning and staying on all the time it will keep the engine from getting very warm an you get no heat.
If the fan is okay, be sure that both hoses to the heater core are getting hot. If those are both okay then the problem is likely the blend door in the heater case.
Hopefully you will have found the problem before you get to the blend door. To get to that you need to remove the dash.
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Friday, November 27th, 2020 AT 11:01 AM (Merged)
Tiny
RANDY PAGAN
  • MEMBER
  • 2003 DODGE RAM
  • 4.7L
  • 6 CYL
  • 2WD
  • MANUAL
  • 169,000 MILES
Replaced thermastat, flushed heater core, checked blend door. Coolant seemes to be not circulating but truck is not runnig hot. Ran the truck apx 10 miles gauge was at temp. About halfway mark. Was able to unscrew radiator cap with no pressure or steam. Coolant was luke warm. Is it possible the heater core hoses were reversed when I put them back on? Is thete a diagram where they connect?
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Friday, November 27th, 2020 AT 11:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

When the engine is at operating temp and the heater is on high, feel both heater core hoses. Are they hot? As far as the hoses, as long as water is flowing through the heater core, it will heat. I attached a pic showing the supply and return hosed on the engine. I have nothing for the core.

As far as the radiator cap, are you sure it is good? It may not be holding pressure.

Let me know if the hoses to the core get hot. If they aren't, specifically the supply hose, something is blocking coolant from circulating through the core. If the vehicle is running at proper operating temperature, then it's getting warm enough to heat.

Let me know.

Joe
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Friday, November 27th, 2020 AT 11:01 AM (Merged)
Tiny
RANDY PAGAN
  • MEMBER
Thanks for the reply back. The supply hose is hot but the return is barely warm. Suspected the heater core was stopped up. I flushed out the core and had heat for about 30 minutes. Then it went cold again. I flushed both directions and had a good stream both ways. Do you think it stopped back up? Does it matter on the core which hose connects where? Does it have an in and out?
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Friday, November 27th, 2020 AT 11:01 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

It may have plugged again. If the return is not hot, it isn't flowing through. As far as the hoses, it really shouldn't matter. Usually one is slightly larger than the other, but I can't remember if that is the case with this truck. It wouldn't hurt to switch them to see if it makes a difference. However, if you had heat for 30 minutes and then it stopped again, I suspect hoses aren't the issue but rather the heater core is plugged again.

Let me know what you find.
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
WILL O
  • MEMBER
  • 2003 DODGE RAM
  • V8
  • 4WD
  • AUTOMATIC
  • 130,000 MILES
Hot air blows out on passenger side of truck/but verry little. On drivers side, cold air blows out with extreme force. Defrost blows out warm air. Temp guage in the truck reads normal.I had the radiator flushed, no difference. Any thoughts?
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
The vent doors are actuated by an motorized actuator it sounds like the mode actuator for the passengers side is out but you can check each of their operation and replace the one that is not working here it the location of each in the diagrams below with a guide that can help as well.

https://www.2carpros.com/articles/car-heater-not-working

and

https://www.2carpros.com/articles/replace-blend-door-motor

Check out the diagrams (Below). Please let us know what happens.
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
GOOD27
  • MEMBER
Thanks for this post I had to get two new acaturos to fix my truck.
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
JAMISONMOBRIANT
  • MEMBER
  • 2003 DODGE RAM
  • V6
  • 2WD
  • AUTOMATIC
  • 95,000 MILES
The heat on my drivers side is blowing cold air while the passenger side is working just fine. On the windshield it seems fine but the floor and dashboard are both blowing cold air on the drivers side but the passenger side is fine. Any Ideas for me?
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
HMAC300
  • EXPERT
You have a plugged heater core. The distribution box is split to each side. The core is only getting hot on the half that feeds the passenger side. Try flushing the heater core both ways it may work if not heater core time.
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
THOP
  • MEMBER
  • 2003 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 50,000 MILES
The heat inside the cabin of my truck comes out just barely warm from the driver's side vent and cold out of the passenger side vents. What could be causing this problem? I've already had my heater core blown out and a coolant system flush and neither has worked. Help, please
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
MERLIN2021
  • EXPERT
Let's say for the sake of arguement, the core is ok, which just because it was blown out, may have worked, then it's possible that the temperature blend door is stuck. The shaft it swings on is metal, and over time they tend to rust and binde up, operated the temp knob while you look for or feel for the actuator that moves that door, some actuators ar vacuum operated, some electrical. Either these motors, called servo motors can go bad or the above mentioned issue! If the shaft is frozen, try a small drill bit at the base of the shaft, drill thru the plastic and spray some white lithium grease in there, if you can move it by hand, so much the better! Work it back and forth till it moves freely!
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
PATRICKACKER
  • MEMBER
  • 2003 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 86,000 MILES
I have a 2003 dodge ram 1500 4.7 v8 one side of the vehicles heating system blows out warm air while the other side blows out cold air and it gets pretty cold driving down the road any suggestions
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Make sure the vacuum lines going to the HVAC system are attached and not damaged.

Let me know what you find.

Joe
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
STREETBOB
  • MEMBER
Hi Joe,
All my vacuum lines are in tact. However, all the mixing doors on the heater are controlled by electric motors. The schematic for the electrical shows wiring to the drivers mixing door. Nothing in the manual shows a view of the box itself. I've found two of the actuators with electric motors, but not the drivers mixing door. I guess what I really want to know is how far down I have to tear down the dash board to get at the right actuator. Will I need to go so far as to remove the passenger air bag and remove the entire backing to get there. I'm hoping someone will tell me what I want to hear. Please tell me "cake walk".
Thanks
Tim
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
That one I can't answer. I will post this with a couple mechanics to see if they have an answer for you.
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Friday, November 27th, 2020 AT 11:02 AM (Merged)
Tiny
STREETBOB
  • MEMBER
Thank you
Tim
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Friday, November 27th, 2020 AT 11:02 AM (Merged)

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