NO HEAT

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

muddyrock

Junior Member
Joined
Apr 11, 2022
Posts
10
Reaction score
3
Location
Tennessee
Ram Year
2003
Engine
5.7 hemi
Hey guys, looking for information. my Frankenstein truck is having an issue. In the last 3 months, I have replaced all the blend doors and actuators in the heater box, all the actuators, the evap core, and the heater core. I figured while I was in the dash, I should get it all. Before the parts, air would not come out defrost or floor vents. It was stuck on face. I had the ac system evacuated and refilled before and after repairs. Since then, the air cycles through the different vents as it should. I also have cold ac now. never checked the heat because I didn't need it at the time. With the colder temperatures, I have tried to use the defrost on several occasions. it barely gets warm at all. I did a coolant flush hoping that it might knock out any debris in the heater core. I did not see any crap come out of the heater core or the radiator. I am hoping i might have just missed something easy. Any help is appreciated guys.
 

Wallyb4

Retired EWC(SW/AW) 1983-2003
Military
Joined
Jan 11, 2021
Posts
268
Reaction score
526
Location
Virginia Beach
Ram Year
2020
Engine
5.7L
Have you tried to reverse flush the core, and only the core?
 
OP
OP
M

muddyrock

Junior Member
Joined
Apr 11, 2022
Posts
10
Reaction score
3
Location
Tennessee
Ram Year
2003
Engine
5.7 hemi
Have you tried to reverse flush the core, and only the core?
Yes. when i did the flush, i pulled the heater core lines apart and flushed them seperately from the rest of the system
when i flushed the rest of the system, i bypassed the heater lines to make sure nothing got back into them
 

mtnrider

Senior Member
Joined
Sep 25, 2014
Posts
3,177
Reaction score
3,434
Location
Georgia
Ram Year
2016
Engine
6.7 Cummins
I doubt the heater core is plugged up already since you just replaced it. Are both line coming in and out of the heater core hot? If so I would lean towards a actuator door not working. There is one that diverts the air across the heater core when the heat is turned on and close's it off when not in use.


.
 

Wallyb4

Retired EWC(SW/AW) 1983-2003
Military
Joined
Jan 11, 2021
Posts
268
Reaction score
526
Location
Virginia Beach
Ram Year
2020
Engine
5.7L
Opps Sorry I missed that in the write up. Also make sure all the air is out of the system, you could have some air trapped in the system.
 
OP
OP
M

muddyrock

Junior Member
Joined
Apr 11, 2022
Posts
10
Reaction score
3
Location
Tennessee
Ram Year
2003
Engine
5.7 hemi
I doubt the heater core is plugged up already since you just replaced it. Are both line coming in and out of the heater core hot? If so I would lean towards a actuator door not working. There is one that diverts the air across the heater core when the heat is turned on and close's it off when not in use.


.
Yes both lines get hot coming to and from. all the radiator lines get hot too and the truck is cooling fine. Im leaning towards air in the system. I just have no clue how to make sure its all out.
 
OP
OP
M

muddyrock

Junior Member
Joined
Apr 11, 2022
Posts
10
Reaction score
3
Location
Tennessee
Ram Year
2003
Engine
5.7 hemi
Opps Sorry I missed that in the write up. Also make sure all the air is out of the system, you could have some air trapped in the system.
Thats my theory at the moment. Not sure how to remove it all. Really dont want to take dash out again.
 

mrbigbill

Junior Member
Joined
Sep 23, 2022
Posts
8
Reaction score
2
Location
Tennessee
Ram Year
2002
Engine
4.7
Find a really steep hill, load ramp, driveway or parking lot and get the nose up as high as you can, run heat and "hopefully" air bubble will move out of core.....as alternative you can take clamp of top heater hose on firewall, take radiator cap off for no pressure and burp at firewall to move air bubble, prestone sells a radiator flush kit that come with a T in it and a screw down cap, installed on top heater hose near firewall gives convenient flush point and "burp" point
 

mrbigbill

Junior Member
Joined
Sep 23, 2022
Posts
8
Reaction score
2
Location
Tennessee
Ram Year
2002
Engine
4.7
Also to note my 02 had similar symptoms and it was bad Tstat, opening all way down near 110deg, truck would heat up to normal after driving a while but little to no heat, replaced Tstat and burp with nose really high and heat will run you out now
 
Top