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Heater control valve delete help

Ridered4583

NAXJA Forum User
Location
Raleigh NC
Happy to be back on the forums after many years. I finally have a couple "new" XJs in the stable. A 91 and a 98. My problem is with the 91. The Heater Control Valve has failed. I have seen many write ups on deleting it, and that is the route I am going as I can not find a replacement part with satisfactory reviews and I don't need this seemingly useless part failing again. My question is, how important is the direction of coolant flow through the heater core? On many bypass write ups I see the 5/8 hose that comes from the water pump being run to the 5/8 outlet of the heater core. and the 3/4 (11/16) run from the T-stat to the 3/4 inlet. This is also the way my 98 without a HCV is routed from the factory. It throws me off though because this will reverse the flow from factory on my 91. As designed in the 91 with the HCV the coolant would flow in the bottom of the core and out the top. In that case I would have to do as shown in a few other peoples HCV deletes and cut and adapt each hose in the middle so it would be a 5/8 in 3/4 out and vice versa on the other hose. So can I just go to the much simpler 97+ style or would I be better off keeping the flow as designed in 91. It would seem in 96 the engineers just decided to do what I am about to and say forget this stupid plastic failure prone piece. So any feed back from anyone who has done an HCV delete would be greatly appreciated.
 
My question is, how important is the direction of coolant flow through the heater core?
There's no directional valving inside the core, its just a copper tube. Connect the hoses so the sizes match.

It would seem in 96 the engineers just decided to do what I am about to and say forget this stupid plastic failure prone piece. So any feed back from anyone who has done an HCV delete would be greatly appreciated.
They also changed the air flow in the dashboard to fully isolate the heater core in 97+. With the earlier years the heater core is always a little exposed, so it will always shed some heat in the air ducts (on my 91 it made the AC run ~15 degrees warmer at the vents, others say they see no change). The warmer air can also make the evaporator cutoff switch come on later, potentially leading to other problems. A lot of people do it, and there's something to be said for the simplicity.
 
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I deleted the valve on my 90 and it did not noticeably change the A/C temp. I did it in my 88 MJ and it did. After fixing the MJ's blend door "gasket" the extra heat went away. I also swapped them both over to an open cooling system.

It also keeps coolant running through the entire system continuously, which I like. Whether it really makes a difference, in the rest of the system, I dunno, but overall I like the "upgrade". Be sure to cap off the HCV vacuum line (pink). I cut it off to about 2" and capped it with a real cap...with glue on it.
 
Happy to be back on the forums after many years. I finally have a couple "new" XJs in the stable. A 91 and a 98. My problem is with the 91. The Heater Control Valve has failed. I have seen many write ups on deleting it, and that is the route I am going as I can not find a replacement part with satisfactory reviews and I don't need this seemingly useless part failing again. My question is, how important is the direction of coolant flow through the heater core? On many bypass write ups I see the 5/8 hose that comes from the water pump being run to the 5/8 outlet of the heater core. and the 3/4 (11/16) run from the T-stat to the 3/4 inlet. This is also the way my 98 without a HCV is routed from the factory. It throws me off though because this will reverse the flow from factory on my 91. As designed in the 91 with the HCV the coolant would flow in the bottom of the core and out the top. In that case I would have to do as shown in a few other peoples HCV deletes and cut and adapt each hose in the middle so it would be a 5/8 in 3/4 out and vice versa on the other hose. So can I just go to the much simpler 97+ style or would I be better off keeping the flow as designed in 91. It would seem in 96 the engineers just decided to do what I am about to and say forget this stupid plastic failure prone piece. So any feed back from anyone who has done an HCV delete would be greatly appreciated.

Use 97 and later heater hoses.

And, ehall is totally wrong about the heat in the cabin when the valve is eliminated on 96 and earlier.

Done half a dozen of them in Arizona. No issues. My AC blows 39.5* out the vents.......
 
I deleted the valve on my 90 and it did not noticeably change the A/C temp. I did it in my 88 MJ and it did. After fixing the MJ's blend door "gasket" the extra heat went away. I also swapped them both over to an open cooling system.

It also keeps coolant running through the entire system continuously, which I like. Whether it really makes a difference, in the rest of the system, I dunno, but overall I like the "upgrade". Be sure to cap off the HCV vacuum line (pink). I cut it off to about 2" and capped it with a real cap...with glue on it.

Come on Charles. You can't keep trumping conjecture with real life experiences!!
 
I may have to try this as I need to get a third control valve this year. Hell, if heat in the cabin in summer is a big deal, you could always run a manual bypass or just not plumb in the heater core in the summer, right?
 
That's it, just block out the stuff that disagrees with your world view. Read again -- "I did it in my 88 MJ and it did"

Not trying to stir things up her;

But I did mention that fixing the blend door eliminated the extra heat. Just sayin'
 
But you did get extra heat which is all I said might happen and which cruiser said would not

Only if the blend door is maladjusted which it about never is!! That takes 20 seconds to check and adjust.

This is getting laughable ehall.

Let it go, would ya?

It works. Myself and others have done numerous HCV eliminations in HOT climates with absolutely no issues.
You. on the other hand keep hanging on to conjecture and hypotheses regarding this.
 
I have IR readings showing 15 degree delta. Why do you think its hypothetical? You act like if you never seen anything then it can't exist. This ain't CF, not how it rolls

"ehall is totally wrong about the heat in the cabin when the valve is eliminated on 96 and earlier."

even when confronted by evidence to the contrary ... absolutist crap
 
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Well, I guess my Jeeps would blow 15* colder AC with a heater valve installed, eh?

That would be 24.5*.Brrrrrrr.

Anyway, ditch the valve, adjust the blend door if it needs it and all is fine.
 
Are your Jeeps all of the world experience combined? [You seem to think so]

No. Not at all.

Many others on all the forums that you piss and moan on about the HCV, have successfully eliminated the valves. Paradise did 2. Not to mention the HCV eliminations I've done for others in my shop.

Not ONE has come back to complain about cabin heat afterward. Just you.

So, you must base your research on one Jeep versus all the others combined?

Believe me, if it didn't work, us folks in Arizona wouldn't be doing it.

Perhaps you need to learn how to adjust blend air doors......
 
Not ONE has come back to complain about cabin heat afterward. Just you.
Good lord man, have you already forgotten the other poster in this thread said they had heat bleed into the AC? This is what's so ridiculous about your position. You say it cannot happen because it never happened to you, other people say well it happened to me and then you say they are conjecture and lying.

I have no problem if somebody wants to delete the HCV. I DELETED MINE FOR YEARS. But there is a chance that the AC will not work as well. That's not a lie. Its not a challenge to your manhood. Its a statement of observable fact.
 
Good lord man, have you already forgotten the other poster in this thread said they had heat bleed into the AC? This is what's so ridiculous about your position. You say it cannot happen because it never happened to you, other people say well it happened to me and then you say they are conjecture and lying.

Only if the blend air door is out of adjustment, usually only because the foam seal has shrunk a bit. EXTREMELY rare.

ONE person said it happened to him. Paradise.

So, based on that, you should poo-poo HCV elimination and ignore all the other benefits? And advise folks not to do it?

Your ego is way too big. Still down to facts and experience versus the lone man on the hill shouting his crap.

And Paradise stated facts. You're the one with conjecture for some reason. Never said he was lying.
 
Only if the blend air door is out of adjustment, usually only because the foam seal has shrunk a bit. EXTREMELY rare.

ONE person said it happened to him. Paradise.

So, based on that, you should poo-poo HCV elimination and ignore all the other benefits? And advise folks not to do it?
WHERE did I advise people not to do it? LOL?

You are making shit up by the bucket just to preserve a position that is proven to be wrong and demonstrably so
 
I did the heater control valve delete on my 94 and its too hot in the cab in the summer.

So my solution was to make a heater core bypass to attach to both heater hoses in the summer. I got the 5/8" hose to 1/2" NPT and 3/4" hose to 1/2" npt nipples at Oreillys for $7 each and two 1/2" elbows(brass) and a 1-1/2" closed nipple(also brass) at the hardware store and made a "U" to attach at the end of the heater hoses. It takes 2 min to switch it over if the engine is cool.

I noticed a HUGE change in cabin temp by bypassing the heater core. My old, never charged, r12 system is happy again and so is the wife.

:cool:
 
I did the heater control valve delete on my 94 and its too hot in the cab in the summer.

So my solution was to make a heater core bypass to attach to both heater hoses in the summer. I got the 5/8" hose to 1/2" NPT and 3/4" hose to 1/2" npt nipples at Oreillys for $7 each and two 1/2" elbows(brass) and a 1-1/2" closed nipple(also brass) at the hardware store and made a "U" to attach at the end of the heater hoses. It takes 2 min to switch it over if the engine is cool.

I noticed a HUGE change in cabin temp by bypassing the heater core. My old, never charged, r12 system is happy again and so is the wife.

:cool:

Have you checked your blend door to make sure it's closing?
 
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