Heat woes continue...

[mwilson]

Yes, and it is extremely frustrating. We have a local shop here, Graft Sales and Service that does my HVAC programming work. They used to be a full line Chrysler dealer until they were forced closed during the Chrysler restructuring.

Basically what has happened to my '07 twice now (besides 2 rounds of broken doors) and now my 2010 1/2 is that for whatever reason, the control head loses its calibration for lack of better terms. When you turn your control to hot, it may move the actuator correctly, move it too far/little, or move it briefly and then allow that actuator to move back, causing the air to go cold. Whatever they do to reprogram it, resets the limits in the head and corrects this issue, provided of course that the doors and actuators themselves are operating properly. Before I would throw any hard parts at the cooling system in that truck, I would seek out a place to hook it up to the computer and at least confirm that everything on the control end is working correctly. I know it's hard to pay for shop to to check something that may or may not be the issue. But, as many times as I've had this happen, it makes sense to me for it to be the first step.

The previous generation of Town and Country / Caravan vehicles would allow anyone with a knowledge of which sequence of buttons to push to perform a recalibration. I had one that flipped out and refused to go to defrost. Did a little reading and found the procedure. Performed it and the issue went away.

The procedure allowed the control head to establish the travel limits of each doors stepper motor. You could hear each motor going back and forth, one by one until finished.

I think by the time the third gen trucks came out it became a dealer only Star enabled function. Maybe the broken doors jam the stepper motor and it all becomes somewhat confused even after the door is repaired???

Mark, it may be worth a shot.....

 

[jgillott]

The previous generation of Town and Country / Caravan vehicles would allow anyone with a knowledge of which sequence of buttons to push to perform a recalibration. I had one that flipped out and refused to go to defrost. Did a little reading and found the procedure. Performed it and the issue went away.

The procedure allowed the control head to establish the travel limits of each doors stepper motor. You could hear each motor going back and forth, one by one until finished.

I think by the time the third gen trucks came out it became a dealer only Star enabled function. Maybe the broken doors jam the stepper motor and it all becomes somewhat confused even after the door is repaired???

Mark, it may be worth a shot.....

I think this is exactly the situation. When I replaced my last set of doors on the '07 myself, I still had to go to Grafts for them to reprogram my control head. I definitely had a broken blend door, but after replacement, it wouldn't calibrate itself, even though I believe they are designed to do so automatically.

 

[sag2]

You can drive the doors each way with a 9v battery. If you access the servo wiring at the control head you just apply power and ground with the 9v and change the polarity to drive the motors in different directions. With the truck shut off you should be able to hear the motor move and stall when it hits the limits of travel. When you get it to the hot position just leave the control head disconnected and the motor will stay in the correct position. If the motor to door connection is broken the door can move when the motor is stopped.
Also pick up a piece or clear hose to put on the heater core as a test so you can observe the coolant flow. You can restrict the hose and watch the coolant rush past the restriction.

 

[sag2]

TechConnect is down right now but this 2006 diagram should be very close to your 2003 wiring.

 

[MarkEagleUSA]

If the motor to door connection is broken the door can move when the motor is stopped.

When I checked everything a few weeks back I wasn't able to move the linkage on the lower door with the actuator in place. When I removed the actuator I was able to move both doors from stop to stop. I could also hear/feel them making contact inside the housing at the end of both directions. I also watched the movement of the doors as I moved the heat control from cold to warm and back again. On Saturday when it was blowing colder air after having been warm, I looked up under the dash and the blend doors were in the proper positions.

Far from scientific and not definitive, but in my mind the blend doors are working fine and are not the problem.

Also pick up a piece or clear hose to put on the heater core as a test so you can observe the coolant flow. You can restrict the hose and watch the coolant rush past the restriction.

I've been thinking about this myself. Not sure where I can get a length of 5/8 clear hose... maybe Home Depot or Lowe's?

 

[MarkEagleUSA]

I understand and please don't get frustrated with me by bringing it up again.

Not at all frustrated. I'm open to any and all suggestions. At this time, based on the troubleshooting I've done, I just feel the problem is elsewhere.

 

[MarkEagleUSA]

If the temp out of the vents drops noticeably when the blower is set to speed 3 or 4, would that be indicative of a flow problem through the core?

I was able to get some clear tubing that I think will work to visually check flow through the core. Just not sure when I'll be able to check that.

 

[petersonj]

If the temp out of the vents drops noticeably when the blower is set to speed 3 or 4, would that be indicative of a flow problem through the core?

Restricted coolant flow through the heater core would cause a reduction in air temperature at higher fan speed settings.

If the heater core is mostly plugged, I would think that with the engine at operating temperature and the heater fan on a high setting that you should be able the feel a significant temperature difference between the heater inlet and outlet hoses. The heater core inlet hose should be very hot and the heater core outlet hose should be cool or even cold because all of the heat would be removed by the high volume of air flowing through the heater core.

If your are experiencing a blend door position problem (such as most of the air bypassing the heater core), then I would think that there would be a much less temperature difference between heater core inlet and outlet hoses because very little fan generated air would be passing through the heater core.

Just another way of confirming what you are already thinking.

- John

 

[Prairie Dog]

My 03 has performed like that since new. I only get a little heat until about 10 minutes of driving.

 

[MarkEagleUSA]

My 03 has performed like that since new. I only get a little heat until about 10 minutes of driving.

I'm aware of the extended warm-up time but this is definitely more than that. The heater output is lukewarm at best after the truck comes up to temperature.

 

[MikeBoisvert]

Good info here: https://heatertreater.net/2008-dodge-ram

 

[MarkEagleUSA]

Good info here: https://heatertreater.net/2008-dodge-ram

Good info indeed. Have referred back to that (along with numerous YouTube videos from others) several times over the past couple of months. I can say that I will resist doing the Heater Treater recommended repair of cutting the HVAC box in place unless no other alternative presents itself.

At this point I have a 15 yr old truck with an unknown (to me) history since it was bought used. I want to remove the whole HVAC box and replace everything (evap, heater core, doors, etc) if for no other reason than peace of mind. The problem is it's not job I want to do in the cold weather (no indoor workspace available) nor can I afford to tie up the truck since I use it to plow my driveway.

 

[smittyd174]

Ram had a recall to reprogram the control head.Dont remember if it was for my 08 or my 10.

 

[jgillott]

Ram had a recall to reprogram the control head.Dont remember if it was for my 08 or my 10.

It was 2009 and 2010.

 

[bboxall]

On my 2001 Ram 2500 one winter I had very little heat. The temp gauge indicated that the engine was running a normal temperature, maybe a little slow to warm up but it would get there. The only time the truck was comfortable to drive in cold weather was if I was towing.
When the HVAC was set to HEAT the air would blow on the floor, I.E. the air blew where it was supposed to but just very little heat so I decided that the thermostat must be bad.

I changed the thermostat and that made NO DIFFERENCE. So, I decided that it must be the water pump. I changed the water pump and then the heat would run you out of the cab, it worked fantastically.

 

[MarkEagleUSA]

I changed the thermostat and that made NO DIFFERENCE. So, I decided that it must be the water pump. I changed the water pump and then the heat would run you out of the cab, it worked fantastically.

I'm actually leaning that way myself. But I want to try and flush the core once more.

 

[hcole]

Do you suppose that there are leaves or insulation in front of the heater core that is restricting air flow across the core fins?

 

[petersonj]

The problem is it's not job I want to do in the cold weather (no indoor workspace available) nor can I afford to tie up the truck since I use it to plow my driveway.

I just replaced my heater core in my '02 truck. I removed the HVAC unit and did all the work on the bench. All control doors (except blend door) are vacuum operated and the system is much more robust in design than the 3rd generation trucks. Anyway, I hear your pain, this is definitely an indoor job.

My heater core started leaking a few years ago so I put some stop leak in the cooling system - something I detest - but I stupidly did it anyway. During subsequent coolant replacement intervals I noticed that the coolant was always cloudy and after it set set for awhile, you could see particulate dropout in the bottom of the bucket. After the heater core replacement a couple of weeks ago, I installed a coolant filter kit and a shutoff valve to the inlet of the heater core. The coolant filter started cleaning up the coolant fast. After 60 miles I drained three gallons of coolant and let it set for a couple of hours - it stayed clear with no particulate dropout. Reflecting back on this, I wonder if a coolant filter kit and a heater core shutoff valve might temporarily help your situation. I say this because you mentioned that one time you back-flushed the heater core and the heater worked much better afterward.

So, what if you back-flushed the heater core again, installed a coolant filter kit, and installed a heater core shutoff valve with the valve in the closed position. Since the coolant filter only filters a portion of the coolant, drive the truck for several miles (at least 50 miles or more if you can tolerate it) before you open the heater core valve.

Of course you would wait for a break in the weather to do this project. Even if it doesn't help your problem, the coolant filter kit is still a good investment.

- John

 

[MarkEagleUSA]

Do you suppose that there are leaves or insulation in front of the heater core that is restricting air flow across the core fins?

In the 3rd gen's, all air goes through the evaporator first before it get to the heater core. When you remove the blower motor you can reach in and feel for any debris, which I've done... even stuck the vacuum up in there to remove any debris. Plus, back during the summer the A/C was nice and cold so I know the air flow through the HVAC box is good.

 

[MarkEagleUSA]

So, what if you back-flushed the heater core again, installed a coolant filter kit, and installed a heater core shutoff valve with the valve in the closed position. Since the coolant filter only filters a portion of the coolant, drive the truck for several miles (at least 50 miles or more if you can tolerate it) before you open the heater core valve.

Of course you would wait for a break in the weather to do this project. Even if it doesn't help your problem, the coolant filter kit is still a good investment.

- John

That's an interesting suggestion. Where can I find a coolant filter? I don't even know what to look for.