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trip98 12-08-2011 10:36 AM

1998 Dodge Ram Heater Core Swap now Issues
Hello Everyone

1998 dodge ram 1500 sport, with AC.

The original heater core had began to leak, I would notice a coolant haze on windows. When driving you would see coolant fumes blowing through the vents. It looked kind of like dust but it was coolant. The heat worked perfectly still.

I purchased a new heater from Advance auto, and began the process. I removed all the bolts and dropped the steering column to be able to pull the dash away. As I got to the heater core area I noticed that the top corner of the core had a large scale build up. Therefore that is were my leak is from. I cut the old tubes of the core and pulled them through the fire wall and let them stay in the engine area until that time.

With the old heater still in the box attached to the firewall, there was a white plastic piece over the actual core. I had to move this by hand in order to pull the old core out.

Now I have installed the new core and was unable to get this white plastic elbow, with a metal wire attached to sit back over top of the new core. The new core also does not sit perfectly flush as the orginal did.

I have put the dash and lines all back together and now the issues begin.

There is no heat, the heater core is very warm to the touch, I have bleed the system numerous time for air bubbles. There are no leaks.

The fan positions all work perfect, fans speeds, and all directional functions work properly.

Now the temperature control knob is hard to turn from hot to cold, I was able to get my hand above the heater core with the glove box removed. I was able to push the metal wire and watch the knob attached to the dash move a bit.

Sorry for the long read, is there anyway I can get the heat to work again?


Okiespaniels 12-08-2011 09:30 PM

Theres a piece of foam probably balled up in the bottom of the heater core tank.My heater core had the same issue untl I cleaned out the tub.

Is this elbow/ wire thing you described a cable? I understood that the blend door is vacum controled. I believe thats a hold down.

The "blend door" which controls the heat form the core, is not functioning. My guess is when you pulled the HVAC unit down, you disconnected or broke the vacum feed line. If you are limber enough, you might be able to get your fingers up near the top of the HVAC unit near the center hump. You'll be able to to feel about until you find the nipple and the hose. reconnect and all should be right.

I wish more people would provide longer descriptions of problems. Intewrnet diagnostics are dicey enough as it is.

trip98 12-09-2011 08:18 PM

Thanks for the info, sorry for the long read.

I am going to pull the dash again, as I fell air blowing out around 1 side of the heater core. Seems like the core is kinda of cock eyed in there.

I will update the thread once the issue is resolved>

Thanks again

DadzDodge 12-18-2011 11:19 PM

You mentioned a white plastic piece sitting over the heater core, that you had to move out of the way. Any chance that it looked like the plastic piece on the left side of this photo? That device is connected to the temperature setting control on the dashboard / instrument panel, and controls the location of the blend door. It's possible you've managed to get it disconnected somehow. When I replaced the heater core last weekend, as seen in the picture, I had to set the temperature setting all the way hot (or cold, I don't remember) so that the white plastic device was fully out of the way. Otherwise, the heater core couldn't be removed because the plastic piece was in the way.

trip98 01-13-2012 09:24 PM

Sorry for bringing up an older post'

Just have an update, I pulled the dash again after getting all the pointers, and the white lever shown in the above post was the culprit for no heat.

The heater core was not seated all the way down, hence the reason for not being able to adjust the heat.

Thanks again all

DadzDodge 01-13-2012 10:23 PM

Hey, good job! The middle of January is a good time to have your heat working again!

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