2002 4.7 heater core replacement Ram 1500

JW1200 · Oct 3, 2015

I have been lurking around since I bought my 2002 Ram 1500 SLT, a couple months ago. It is looking like I need to replace my heater core, and I want to do it before winter hits. I have a wet passenger side floor, and the windows steam up a bit while running the defrosters in heat mode.

I have done all the searches and have read all of the threads about the Gen3 1500 4.7 heater core replacement on the forum. There is good info on this forum, thank you. Looks like I have to pull the whole dash, and the steering column.

My question is..... Today while I was testing the heat system, I had the AC/Heat, dial, all the way to the red, heat side, and the AC button (yellow light), OFF . I noticed my AC compressor was still kicking on and off. That don't sound right to me. Does anyone have any advice about the compressor kicking on and off? And does anyone have a link to a good video to pull the dash to replace the heater core? And final question, Do I have to discharge the AC system to replace the heater core only? Thanks guys!!

sylver91 · Oct 4, 2015

Yes the compressor will cycle with the heat and defrost. It helps pull moisture away when warming up the truck otherwise the windows wouldn't de-fog quickly.

As for the heater core I don't think you need to discharge the A/C as I believe the HVAC housing is separate. What I do remember in some of these trucks are hidden nuts on the firewall, one near the heater hoses and another I believe by the PCM bracket.

Also Chrysler products are picky when it comes to heater cores. In the past I've had nothing but trouble with after market cores with different inlet/outlet lengths and sizes as well as different shapes which lead to unequal or poor heat. Stick with an OEM core.

JPT · Oct 5, 2015

When my heater core was replaced (had a shop do it under aftermarket warranty), it DID require discharging and recharging of the AC.

JW1200 · Oct 6, 2015

Thanks for the reply's, guys. I'm going to start on it this morning.

hotkarl · Oct 6, 2015

While you have the dash ripped out change everything. Blend doors. Evap core, etc. one and done.

SilverStreak88 · Oct 6, 2015

JW1200 said:
Thanks for the reply's, guys. I'm going to start on it this morning.

Have fun.... I did it a month ago.

xb1230 · Oct 7, 2015

+1

hotkarl said:
While you have the dash ripped out change everything. Blend doors, Evap core, etc...

Check also that all the Blend doors actuator motors (3 of them) are working well and I would replace blower motor resistor as well. It is easy to get to without taking off anything, while you are at it, and have everything in your hands you can make your HVAC system worry free for the rest of the life of the truck.

From a Blend Door perspective, give a look at the "Heater Treater" kit. This is an aftermarket kit that will resolve any potential issue with the door system once and for all... well worth the money.

Make sure you discharge the electrical system properly before removing the dash and steering column to avoid triggering any of the airbags.

Have fun!

HemiLonestar · Oct 7, 2015

Enjoy...did around this time 2 years ago. If you have a cracked dash this is the time to get a replacement and install it (I did).

JW1200 · Oct 7, 2015

Thanks guys. I'm still in it, I have everything takin apart and out of the truck. And yes, you have to remove the HVAC box out of a 2002 and , you have to discharge the ac and remove the lines that go thru the fire wall. Oh, what a joy!!

I am going to the stealer, ( Chrysler Dodge Dealership) in the morning to get a new OME heater core. My ac evap deal was kind of dirty but it don't look bad. I sealed the connections and washed it with a water hose. The ac was working before, so I'm thinking, I'm good? What would you do? I would hate to take this sucker apart again, so I hope the evap is good to go.

Any comments are welcome.

SilverStreak88 · Oct 7, 2015

I did mine without removing or evacuation.

JW1200 · Oct 8, 2015

SilverStreak88 said:
I did mine without removing or evacuation.

Dang, good on you lucky dog!!

I hear tell there are 2 kinds of the 2002, the old body style, and the new body style. Sounds like I have the later.

JW1200 · Oct 8, 2015

Done.......... Everything seems to be OK with the heater core, job. I hope I never have to do that again!!

JPT · Oct 9, 2015

Mine is under the knife right now. I got the heatertreater.net door kit (all 4 doors). My shop is replacing all the doors in the system, as I was only getting heat on the passenger side. So since they had the dash out, I wanted to not have this problem again...

sylver91 · Oct 9, 2015

SilverStreak88 said:
I did mine without removing or evacuation.

Thats what I thought, maybe its just in the 06-08 trucks.

SilverStreak88 · Oct 9, 2015

sylver91 said:
Thats what I thought, maybe its just in the 06-08 trucks.

I should have... I would have... had I had the vacuum and gauges. I was a total pain, pure hand to mind coordination on the back screws.

JW1200 · Oct 9, 2015

SilverStreak88 said:
I should have... I would have... had I had the vacuum and gauges. I was a total pain, pure hand to mind coordination on the back screws.

That's the route I wanted to go, but it was just to tight. My SIL is a hvac tech, so I got him to do that from me.

Also my blender doors looked fine, so I did not replace them. They still seem to work fine.

I also put a ball valve in line to shut off the coolant flow should I have another heater core leak.

SilverStreak88 · Oct 10, 2015

JW1200 said:
That's the route I wanted to go, but it was just to tight. My SIL is a hvac tech, so I got him to do that from me.

Also my blender doors looked fine, so I did not replace them. They still seem to work fine.

I also put a ball valve in line to shut off the coolant flow should I have another heater core leak.

The only door that has broken on mine is the mode 2 door. I fixed it when I was in there but the I got that was said to be the same was actually the blend door.

I fixed it with a self tapper and it worked great for all of 2 cycles.

JPT · Oct 10, 2015

It is too bad while you were in there you didn't do the heatertreater fix. It seems like the doors are a ticking time bomb. If you ever open up the dash again, I would suggest replacing all 4 doors. It would have saved me time & money if I did this last year when my heater core was replaced.

2002 4.7 heater core replacement Ram 1500

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