Hey folks,

I have a 2001 RAM 1500, 148k miles. I replaced my Radiator and A/C this summer. Now it's getting mighty cold outside and when i try and turn the heat on after running quite a while all I get is luke warm air at best. Mostly from my middle bi-level vents, colder from the side vents. When I did the work this summer I got freezing cold air from all vents like a champ. That makes me learn towards the heater core, as in my mind if the blend door was not actuating I would not be able to control my temp one way or another. I know from threads similar on here that checking the actuator is quick and easy, but so is trying to flush my heater core. Just wondering based on my symptoms which you would tackle first, since I have limited time this close to Christmas.

Thanks.

 

side note, the truck runs at a good temp, never overheats. I hear my thermostat open up when it should, and the lines to the heater core do get warm/hot as they should.

 

Were you successful with burping the air out of the cooling system?

 

Back flush the heater core first.

 

Thanks for the replies.

fj5gtx - Do you mean when I replaced the radiator this summer? We burped the system at that point and have had no issues with temp of the truck in general.

HeyYou - That is the plan, especially based on the below.


I have been working on this all morning. Last night I was unable to hear the blend door and thus the post. Since then I gave it longer after changing from full cold to full heat demand and can hear the blend door move and the air temp shift from full cold to luke warm. Also I feel like I can hear slight gurgling from where I now know the heater core is located, which tells me I think I have quite a bit of gunk in there. I felt the inlet and outlet temp, both get very hot with the heat not on. If I then turn the heat on I get a quick burst of pretty warm air which cools very quickly, and the outlet line cools down quickly as well. I think this tells me I have bad flow through the heater core (like barely any). My plan is to try and flush the heater core, although I have very few tools on hand to do it even though it seems very easy. When I flush in the outlet and out the inlet what do you recommend I put in and let sit to eat up the gunk? I have heard CLR and other suggestions. Also, the biggest thing I am wondering, after I finish and hook the system all up again (after flushing multiple times the cleaner I end up using etc) do I run the truck with Rad cap off and top it off that way? I want to avoid introduction air into the system when I do this. Thanks in advance for the help folks.

 

The auto parts store by me wanted me to do a full radiator flush, which I want to avoid since it's a new radiator.

 

I think I'd pull both heater hoses and use a garden hose to back flush and then forward flush the core before putting any chemicals in it. See if its flowing or not. If its not flowing, then try the chemicals. Of course, with old man winter in full effect, might not be possible with water.

 

so I did a back flush with air first. Got a bunch of rust and junk out. Then did clr soak, then flushed multiple times with water. Then hooked it back up and it’s running like a champ. Thank goodness to avoid a full heater core replacement.