Guess I've been lucky with mine. Only other component problem was a failing fan clutch when I first got the vehicle. I hadn't worked on or driven the thing in quite a few days when I noticed coolant under it. HCV just gave up the ghost on it own. After that I replaced the entire cooling system (11/16).

 

my hcv is a couple of years old, I had changed it because it was leaking (crown brand).
When I adjust the temperature, her arm moves well.
Do you still suggest to delete it?

 

Here's the thing. If it's working fine ok but for some reason the factory eliminated them. Fact is that if it's eliminated coolant will flow through the heater core constantly when the vehicle is being operated keeping it flushed out but not affecting the heat or a/c at all.

 

Have you tried back flushing the heater core, blowing it out with a air chuck @ 25-30 PSI, filling it with CLR or some other calcium/rust remover, back flushing it again and repeating the process?

I serviced my entire cooling system and got it running pretty good but the heater core was so backed up that I had to remove the inlet and outlet hoses and do some more in depth flushing. The first flush was pure sludge, the second flush was basically just red rust ***** and mineral build up, I got it to actually cook in there by doing this.

 

This is my guess why they stopped using the HCV. The heater could have the same coolant in it for long periods of time if heat is never used allowing it to go nasty in there.

 

I wondered around the home improvement store and build an adapter that lets me plug the garden hose right into the heater hoses. Works incredibly well for flushing the heater core with ease. Its a ball valve hose adapter with a brass adapter to fit in the heater core hose. The ball valve allows me to control the water flow.

 

Can anyone guess how I know its winter time in the Northern Hemisphere?
You can see it all over the forum hahahah
I know it sucks, but troubleshooting your heater system in the later spring or early Fall when its not so cold out is probably the best idea I've ever heard of regarding an XJ. Then you dont have to drive around in a cold, or barely warm cab for 4 or 5 months... or scramble to get it fixed when its already cold out...
I learned this lesson myself last winter. Now if I could just get the air to get warm FASTER, I'd be completely satisfied. I dont think I have anything acting up in the system preventing "HOT" air from coming in, it just takes three times as long as my wifes Durango to get hot air in the cabin..

 

In my case it was a Florida Jeep and the backwoods ***** decided to keep water in the coolant system for as long as they could. When we first got the 97, my GFs brother flushed it and the stain of rust that was left behind when the water evaporated was something else.

I kind of did this too. I have two adapters. 5/8 and 3/4. I will interchange the hose and do whatever as I please. I did get a a nice piece from a coolant flush kit that basically regulates hose pressure which I think is a important component to flushing the heater core.