Hi All,

My name is Chris and I am new here. I searched the threads for my specific topic but did not find the information I sought. As you can see by the title, when I bought my 2000 XJ, it already had the heater core deleted. The question is, "If I have a heater core delete, what other components will I need to replace the heater core and get the heat working again besides the heater core itself." I am pretty good with most things mechanical, but I know nothing much regarding AC systems and heaters. I already picked up a heater core (I couldn't find a copper one) but have landed on one that will do the job. Before I start digging in too much, is there anything else I am going to need? If this helps, I still have AC, just no heat.

Thanks,
Chris

 

Since the heater was not optional, that's going to depend on what you mean by "delete". None of us can know what the PO did. Pictures will help here.

The only reason I can think of to delete the heater core to eliminate a leak without actually fixing it. Taking the Jeep that far apart just to remove the weight of a heater core makes no sense to me. If all they did was loop the heater coolant hoses in the engine bay and you can still see heater core tubes next to the AC lines, it will be as simple as hooking up the hoses and replacing the probably leaky heater core. I'd plan on replacing the heater core, heater hoses, the foam seals to the firewall, and otherwise giving the entire HVAC box a thorough clean, lube pivots, and make sure your blend door is in tip top shape.

Be careful and thorough with reassembling the box, and verify function as best you can before reinstalling it, or you might end up pulling it a second time like I just had to.

 

So, I guess maybe I should use the word bypass? Honestly, I have no leaks and I have no heat so I am not sure. Anyway here are some pics that I hope will help.

 

Your heater core is hooked up correctly. You most likely either have a clogged core or the blend door isnt working.

 

After warmed to operating temp, both hoses should feel very hot (be careful if you use touch to test them). If not, then likely the core is clogged. If they are both hot, then likely the blend door is the issue. Just as 5-Speed says.

If it's the core, you can try removing the hoses and flushing the core. Go easy on the water pressure. Flush from both directions.

The blend door operates on a stepper motor that blocks off airflow through the core when the temp setting is turned to "cold" (like when using the AC). As you turn the temp dial to warmer, the blend door swings and allows air to flow through the core. You can look up under the dash behind the glove box and see the motor. If it's the blend door, it could be the actuator (motor) is bad, or the "axle" for the door, that fits into the motor has sheared off.

So you need to determine if it's the core or the blend door.

 

Start by giving the heater core and the engine itself a thorough flush. The 4.0 loves to rust internally. I've pulled a tennis ball's worth of rust detritus from behind the freeze plugs on a 4.0, even after flushing it twice.

Don't put a new radiator or heater on a 4.0 without doing a flush, you'll just start filling the new parts with gunk immediately. I didn't hook up my heater core for months after putting it in, I replaced it with a coolant filter until I was sure the system was clean.

 

So, I have flushed the heater core and I now have heat. I may take on the replacement at a later date, but for now, I am going to leave it where it is. Subsequently, I also removed a jerry-rigged XM radio antenna and I am not sure if some of the water from the flushing knocked out my electric cooling fan or if I blew a fuse removing the antenna. I will be going through the fuses first and then hoping that it is just a little water that will evaporate. Not tackling this till tomorrow though. Got heat! Now my ice-cold AC is gone completely just hot air.