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Removing the heater control valve on a '96 XJ

bradleyheathhays

NAXJA Forum User
Location
Lexington, KY
I've been told to completely remove my heater control valve. Never having dealt with this before I'm assuming this is it...

valve%20pic_zpsxmsmbn7i.jpg


I guess all that's involved is just to remove this valve and re-connect the remaining hoses. Not sure exactly how those connections would go though. Hoses A & B both go to the heater box and hoses 1 & 2 both go to the motor. Here's where the top hose #1 goes...

front%20line_zpsb1dxouzb.jpg


If I knew what direction the water flowed in that last pic (to or away from the water pump) and which way the water should flow through the heater box that would be enough info to know how to hook the hoses up. I'm guessing the flow through the heater box is 'IN' through the bottom inlet and 'OUT' through the top outlet (in order to let air bubbles escape).

So am I getting this all about right? In what combination should these hoses be reconnected?
 
The hoses are different sizes, and the heater core has appropriately sized fittings. One of them is 3/4 the other is 5/8.

The heater core doesn't have any internal valving, so there's no right way or wrong way. Just match the hose size and move on.
 
When you go to take the hose off the heater core inlet/outlet its best to cut a slit on the hose then take the hose rather than just trying to pull the hose off the connector you can destroy the heater core fittings if your not carefull.
 
Update is I measured the OD of the two hoses with a dial caliper and both of mine measure just about .89" so not sure what's up with that. I'm the 3rd owner so maybe they've been modded before I got it, not sure.

Further update is that I've decided not to take the valve out. Reason I was doing this in the first place was that I have a separate a/c problem occurring and in doing some research found some threads where guys were suggesting to remove the HCV altogether citing reasons like in summer no coolant (with anti-corrosive properties) was being circulated through the core, etc. But after looking into this a little more I've seen suggestions that the valve should be left in as it will compromise my a/c if hot coolant is always moving through the heater core while the a/c was blowing, just like you're saying Diesel. Makes sense. I'll have to do a separate thread on the a/c problem.
 
The heater valve is normally open. It is pulled closed by vacuum pressure when HVAC controls are OFF or in COLD zone. Even in the dead of summer, when the engine is shut off the vacuum releases and the valve opens and coolant floods the core.
 
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