My heater seems to blow cold on the driver's side and "luke warm" on the passenger side

2002 DODGE RAM
100,000 MILES • V8 • 4WD • AUTOMATIC
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SHASKINS
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My heater seems to blow cold on the driver's side and "luke warm" on the passenger side. I have pressure tested the system and there does not appear to be any coolant leaks. Also, I have pressure filled the cooling system numerous (6?) times. Each time it seems to work better for a little while, then goes back to not working well and blowing cold on the drivers side.

Any thoughts? I would have thought blend door problem, but that doesn't make sense that it works better after pressure filling. Is it possibly that heater core is just too clogged and not "flowing" well enough to where only air directed to passenger side gets warmed?

I should note that I have the single zone climate control (no dual zone) and it is the 4.7L engine.
Feb 10, 2010 at 11:56 PM
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2CARPRO JACK
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If they share a common plenum, there shouldn't be any reason for it to be cooler on one side.Check the heater hoses to be sure they are both hot with engine warmed up, you may indeed have a flow problem keeping the system from getting hot
Apr 23, 2021 at 10:36 AM
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SHASKINS
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THese are the heater hoses going to the firewall from the engine/radiator? I should just reach down and feel them while the engine is warmed up?

What would you recommend if they are hot vs not hot?

Thanks,
Scott
Apr 23, 2021 at 10:36 AM
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2CARPRO JACK
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Yes, those hoses.They wont be scalding hot, just tap them first to see how hot.If the engine is up to running temp, the hoses should both be hot, if not you may have a flow problem with the heater core
Apr 23, 2021 at 10:36 AM
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SHASKINS
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I checked the hoses and they seem to be hot after the engine has been warmed up. Not sure how hot they should be, but very warm to the touch after a couple of seconds.

Since the hoses are hot, does that imply a problem with blend doors or actuators? Also, I noticed that it seems the air blow a little stronger on the driver (cool) side as well.

If blend doors or actuators, is that a part that I can readily get?

Thanks,
Scott
Apr 23, 2021 at 10:36 AM
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2CARPRO JACK
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Yes, the parts are readily available, its usually access to them that is the problem.Some may require teh entire dash to be removed to get to them. Try going from hot to cold with temp selector, you should hear a noticeable change in sound of air flow, if not the blend door actuator may be bad, not moving from the a/c evap core to the heater core. If there are any issues with vent selection, the mode door actuator could be at fault
Apr 23, 2021 at 10:36 AM
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SHASKINS
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Interesteingly enough, it seems that the air goes from hot to cold and changes location (floor, defrost, vent, etc.) with no problems.

The only "problem" with the system is that the drivers side blows cool and the passengar is warm.

Could this still be a blend door?
Apr 23, 2021 at 10:36 AM
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2CARPRO JACK
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Not likely.. check the ducting under the dash. did this just happen all of the sudden?
Apr 23, 2021 at 10:36 AM
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SHASKINS
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No...it was not all of a sudden. There seems to generally be airflow and it will direct air to the right vents (defrost, vent, floor, etc.) when changed.
Apr 23, 2021 at 10:36 AM
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2CARPRO JACK
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If it is all good mechanically, you may need to get under the dash and give a real good visual inspection to see if something came loose or is obstructiong the flow from the heater
Apr 23, 2021 at 10:36 AM
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GOOBERS_GARAGE
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It most likely is a temp blend door problem.

check out heatertreater.net
Apr 23, 2021 at 10:36 AM
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2CARPRO JACK
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Thx
Apr 23, 2021 at 10:36 AM