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TJ Heater Core Replacement
for 2001 TJ 2.5L engine
by Jason Fjeld
 

14. Your Jeep, however, now looks like this:

Figure # 3

15. If you have air conditioning, you need to discharge and recover the a/c refrigerant (i.e., �Freon�, although that specifically, is no longer used). You then need to disconnect your refrigerant lines from the evaporator. This is necessary since the entire heater / a/c housing assembly will be removed from your Jeep.

I�m really not going to detail this since the EPA has gone to great lengths to protect our ozone layer from this stuff.
Suffice to say that these steps would best be performed by a professional. [See Figure 4]

16. Disconnect both heater hoses from where they enter the interior cabin. Notice that the top hose is larger in size, while the lower one is smaller. Take note of the hose orientation. The two ends of the spring clamps may be squeezed using a channel-lock pliers. Note that you may need to twist the hose to loosen it up. A coating of warm, soapy water may also do the trick, although you should avoid getting this into any openings. [See Figure 4]

17. Disconnect the vacuum supply line connector. [See Figure # 4]

18. Remove the L-shaped evaporator drain tube that protrudes from underneath the evaporator canister.

 

Figure # 4

19. Remove the five (5) HVAC housing-to-chassis nuts using a 7/16 socket or wrench. [See Figure 5] They are found (when viewing from the engine compartment):
� To the left and bottom of the blower fan (1)
� Holding the evaporator canister bracket (2)
� In the middle, above the engine (1)
� In the middle, just above the cylinder head. Note that this one holds the cowl plenum drain tube. The nut holding the drain tube must be removed, the cowl plenum drain removed, and then there is another nut underneath. (1)
 

Figure # 5

20. From within the cabin, remove the floor duct from the bottom of the HVAC unit. This can be done by removing the two (2) front and one (1) rear screws with a 7/16 socket or wrench. The duct can then be slid to one side and removed.

21. Remove the screw holding the HVAC unit to the firewall bracket, near the fuse panel, using a 7/16 socket or wrench.

22. Straddling the center console, slide the entire HVAC housing toward you, being careful to clear the center air ducts. Remove the entire system and place in a suitable area where you will now begin the disassembly.

23. Using a 7/16 nut driver, remove all screws holding the upper and lower HVAC housing halves together. Gently remove the top cover of the unit. I�ll be honest; I had a lot of trouble here and had to gently pry the thing apart.

24. Remove the leaking heater core from the housing. When viewing the HVAC unit as it appeared in the cabin, the heater core runs across the back from the left side to the middle, where the tubes exit the housing.

25. If possible, clean the housing of any oil/antifreeze leftover from the formerly leaking core.

26. Replace the leaking core with the new unit.

27. Refit the upper and lower halves of the HVAC unit together and replace all screws.

28. Repeat all prior steps in the reverse order to reattach the unit, refit all hoses/lines, reassemble the dash, and reassemble the steering column.

29. Replace your coolant or have it flushed by a professional.

30. Crack open a cold one and give yourself some credit. Use the $500 you saved and treat your Jeep to some new goodies.

 

Update:  02/06/2010

Stu's comments - I recently received an e-mail from MikeP, one of folks that use the site, regarding Jason's heater core write-up.  MikeP said: 

Stu,

I'm about to re-assemble from Jason's write-up of the TJ Heater core replacement project.  I wanted to pass this along to you in case you wanted to append it onto the write-up.  I followed his instructions but I have a 4.0 with a/c and had a couple of workarounds.  By the way, that was probably the best write-up I have ever followed.

So with that being said, here are MikeP's comments regarding the heater core write-up.

I don't know how old the write up is but it was an excellent piece of work.  I just followed it for my 01,Wrangler Sport TJ 4.0 and with a couple of exceptions, it went smooth as silk.
 

If you want to add the changes, here they are:

On the five firewall nuts, there is a sixth one stacked under the drain from the louvered air intake in the hood.  It is lower nut on the firewall right behind the valve cover on the 4.0.  It was just a surprise when the unit wouldn't come out.

The third screw in the back of the floor duct was easily removed with a 5/16 brake bleeder wrench.  Would be even easier with one of those ratchet-type box wrenches.

And lastly, my a/c was already discharged but I didn't have a clue about the a/c line disconnects.  After some Googling, I bought the plastic a/c discharge tools (6-pack of colored plastic rings) from Harbor Freight for 7.99.  Worked like a charm!  Tried the metal x type wrench first but it was just flat lousy.  I also removed he defrost piece held by two clips in the firewall and the unit slid right out.

Thanks again!