Originally Posted by [meph]

FYI it is prolly your doors.. My dads truck had the same issues. the doors may seem to be working fine, but did you check to see if the limit tabs are still intact? If not, the motors and doors will not work properly.. i literally just finished up my dads 03 ram this afternoon changing out all of the doors.
http://www.heatertreater.net/Ram%2002-08%20Listing.html <-GREAT ppl with METAL replacement parts. they also include a very detailed instruction book. you DO NOT have to take the entire dash apart to change these. only the surface (the pretty stuff) has to come off. Then a little creative cutting/replacing/taping and you are done. It took me 6 hours to change out all of the doors and everything works fine now.

i recommend you take a look at that site and read up on what they have to say. i tried to call BS on my pops until i actually tore into the truck and noticed that everything that company said was very true. good luck

Originally Posted by 45s4life

On my o2, I checked my blend doors based on a company that sells replacement doors and provides a video on checking and replacing them. My doors seem fine, however, when checking to see what else may be happening, I noticed the motors didn't turn when I turned the ***** on the dash. I took one on the motors out and supplied 12 volts and it spun with no problem. I'm thinking the control head on the dash may be bad. $160.00 from the dealer. Putting my funds together. I haven't figured out anyway to test the existing control head after removing, so I guess I'm stuck replacing and hoping that fixes it.

Originally Posted by Caseys-dodge

As the heater core ages it deteriorates and corrodes and gets calcification buildup (might not be proper term). The main problem with using CLR or other products to get rid of the last 6 years of use is it may clean off stuck some stuck on deposits and uncover small holes and then create leaks.
The manual specifies that our trucks use a HOAT only coolant (dealer only mainly) but I think NAPA auto stores sell a HOAT coolant as well for a little bit cheaper. I think it's a pinkish color.
When I did my flush (I replaced the water pump) I drained the radiator and engine block, removed the t-stat. I disconnected all the hoses and just used a garden hose to shoot thru the heater core hoses, thru the engine block in both directions and thru the radiator thru the top only. Some of the bigger hoses made it a messy job because I just used my hands to "seal" the garden hose up. Certainly not a fully pressurized job, but plenty of water made it thru and once it started coming out clean I felt the job was good enough.
That is an overflow tank that you were referring too. Somehow the entire radiator system is pressurized, except for the overflow tank, but the two are connected by a plain rubber hose. Supposedly as the system heats up and cools down the level in the overflow tank will fluctuate. Also if you have a slow leak it will drain the excessive from the overflow tank first before the level in the radiator gets low.
I'm not sure what metal the heater core is made of...

** oh yeah. When you're refilling with new coolant, start with the radiator. Go slow because it may splash out. Once the rad. is completely full fill the overflow tank to the full mark, or about half of the tank. Again top off the rad because it will slowly drain into the engine. Close everything up and let the truck run until the t-stat opens up and coolant is fully circulating. That's when both the upper and lower rad hoses will heat up, also good to have the heat turned on in the truck. When the truck cools down completely check the level in the rad and overflow tank and top off as needed.