Dodge ram with poor heater

Bruce Reimer · Dec 5, 2009

I have a none tractor problem. My '03 Dodge Ram does not heat worth a hoot. The temp. gauge shows pretty much straight up and we ran a hose through the heater core and have unobstructed flow. It's just a little below freezing and I'm running the heat at max, it feels like the knob should turn around further. Is there possibly a flap problem? I understand that Dodge hung the heater core up in mid air and built a truck around it, dealer says it's a full days job to replace it, don't feel like it just to eliminate a possible problem. That is my only beef with this truck, over 200,000 kms and been good otherwise. Thanks for input; Bruce

mike321 · Dec 5, 2009

Is it a diesel? I have an 03 dodge with the cummins and mine heats great. Could it be you have air in the system? Are the heater hoses warm?

Anonymous-0 · Dec 5, 2009

Possibly related, but not sure.. My 01 had an issue with the AC blowing hot air if I hit a bump in the road.. I got it diagnosed just before the warranty ran out at 36K. Turned out it was a plastic cam that cracked, this cam controls the hot/cold ratio flap. They had to order the cam, so I took it back later to get it fixed.. It was completed in an hour or so.

Michael Soldan · Dec 5, 2009

My 2001 GMC quit heating and I took it into a shop, they flushed the heater by removing the heater hoses, a lot of crud builds up in the core, they flushed it good and my heater performs like new..you need to start with a good flush of the core. As suggested , if the heater hose coming out of the water pump is hot, you have a plugged up core

Old Timer in Ohio · Dec 5, 2009

Hey there Bruce;
Why don't you get a Haynes repair manual?
They have a "trouble shooting" section in
there. Or you might find one at your local
Library, you might be able to sign it out.
Bob
God Bless

Bruce Reimer · Dec 5, 2009

4.7 gas, yes the hoses feel nice and warm but not uncomfortably hot. Understand these engines have the thermostat in the bottom hose and the flow is bottom up rather than top down like most others.
Bruce

Anonymous-0 · Dec 5, 2009

I've got a 2000 Chev with a 6 litre that doesn't put out much heat either, even with a new thermostat. I think I'll have to get a cooling system flush and see if that helps. Dave

ncdiesel48 · Dec 5, 2009

A friend of mine had the same issue, we back flushed the heater core all you need is a half inch barbed fitting and hook it to a garden hose it takes about ten minutes to do, worked like a charm.

Bruce Reimer · Dec 5, 2009

Like I stated, we ran a hose to the core and watched what came out, the water was clean and flowed freely., Bruce

burban2002 · Dec 6, 2009

The blend door could be malfunctioning and allowing cold air into the cab.

onefarmer · Dec 6, 2009

I tried the garden hose trick a few times and got mixed results. What I do now is get the hoses loose from the engine fill the heater core with water and blast flush it with an air hose. A nozzle with a LOT of VOLUME. Do this a few time both directions. And no I haven"t blown up a heater core yet!

2x4 · Dec 6, 2009

Strange. I've got 2000 Chev w/6.0, 4 door, & heater will run you out of there. That is the year they used cast iron heads on 6.0. All other years have Aluminum heads.

Anonymous-0 · Dec 6, 2009

Check the heat/cool control knob. Sometimes when turning the temp. to hot or cold it will crack the back side of the knob in one of the corners. So when you try to turn it to hot it slips on the shaft. I have seen this on two dodge trucks.

El Toro · Dec 6, 2009

If that heater has a flapper door used to dump the heat when it's too hot may be obtructed. I had a 78 Chevy 3/4 ton used on construction and couldn't get any heat. I called the local Chevy dealer and they said to check that flapper door.
I found handfuls of pencils & ball point pens in
there. That fixed the heater problem. I guess they just threw the pen sand pencils up on the dash and wondered why they disappeared. Feel the heater hoses if they're hot I don't think the core would be blocked. If the feed hose is hot and the return hose is cold then you have a blockage in the core. Hal

Anonymous-0 · Dec 6, 2009

mixing valve under the hood, in the water line is possible not opening enough to get good flow, or no flow.
Kevin

ACKen from Wisc · Dec 6, 2009

I had that problem with a 97 Dodge and after two winters of low heat, I changed the radiator. That fixed my problem. I thought that I had flushed the system good enought too.

BushogPapa · Dec 6, 2009

Would be a good idea to maybe replace the thermostat..
If it will open at anything below 195, it will make a huge difference in heater temp..
If it opens at 180 or less, you will not get a lot of heat at all..

ScottyHOMeY · Dec 6, 2009

Thre was a problem during those years with the actuator breaking the door that routed the air from the blower.

ncdiesel48 · Dec 6, 2009

If the fan is running in the dash and you only have defrost then it IS the mixing door. Which is an 8 hour job to fix.

RickieBlue · Dec 6, 2009

I had a '94 Ram and the temp control knob wasn't turning the control properly, it was slipping....had a buddy with a '76 or so Dodge and it didn't have good air flow coming out of any of the vents....after freezing for a 96 mile ride, we took a peek and the heater box was full of shelled corn....darn varmints anyhow...LOL

Bruce Reimer · Dec 6, 2009

Thanks all for responses, will try to zero in on the issue, wish the heater was easier to get to. I guess they needed some way to keep the service dep. going.
Bruce

Anonymous-0 · Dec 6, 2009

It used to put out good heat. I think a good flush would probably help a lot. Dave

Anonymous-0 · Dec 7, 2009

More than likely the little seal on the mixer doors in the unit. It comes off in little pieces as it gets older. Mine did that years ago...it will heat the cab in time...it all comes out...just not exactly where you want it.
You may try cracking the window just a little...it helps to get the air moving a little better.

omahagreg · Dec 7, 2009

On my Brother in Laws V10 Dodge, the thermostat had self destructed. It could not open. Replaced it and now it is fine. Greg

Raysflhs · Dec 7, 2009

Response may be too late, but I just had the same problem with an '06 Ram 3500 this fall. Probably same design as an '03 & dealer guessed problem right away. A broken door/flap on HVAC costing less than $100, but costs over $900 to fix because they have to take the whole dash apart to get at it. Still paying for that, but at least I'm warm now. Ray S.

rustyj14 · Dec 7, 2009

I had that problem with my Dodge Mini-van. At the place where i worked, we found that drilling a small hole in the heater box, under the dash, and several long squirts of WD-40, or such, would free up the flapper door and heat would come back! Hole was not near the heater core.
Never had that problem with any of my lawn tractors, tho! ;0)

Dodge ram with poor heater

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