HEATER VALVE... do I REALLY need it?
 

1990 XJ 4.0 4wd...

Just finished replacing the head gasket....

While messing around in there, the plastic heater valve busted, so I just cut it out and ran system with no valve.....

With all the nastiness that I've been reading about these things...I'm wondering...do I really need it?

I'll also be switching to the open system this summer. Before all that I have a laundry list of fixes to concern myself with first....new brakes, rear wheel cylinder, rear hatch lift supports, blower motor resistor, shocks, ball joints, tires, a wiring mess the last owner made....high idle issues....lol

Anyway....so....do i really need this valve? Or can I just eliminate a weak point of the system (as I see it) alltogether?

Thanks all...

Depends if you want heat on all the time or no heat at all.
You could also put a on/off turn ball shut off valve inline and manually turn it
when you want heat or no heat.
I have seen dozens at the wreckers and it's the kind of thing they don't even charge for.
As long as you don't bump them too hard when they get old they work well enough.

I was about to suggest the same thing, if you're wanting to go the cheap route. My dad did this once on an old car and left it open during the winter. If we happened to get a little too warm we would just crack the window a bit. Like you, he just had other things to spend his money on at the time so it was an effective cheap fix.

So I've been in the dash in GOD KNOWS how many cars, I've heard of these valves, guess I've just never really seen them....

Isn't there a blend door that does the work of mixing/regulating the flow of air either over the heater core or evaporator?

What I'm gettig from you is that if I eliminate thisthi g fom the system entirely, durin the summer I'll have the ac fighting the heat?

Gotta call it how I see it....crap design there.... Kinda like taking the dash off to do a heater core (chev s10's/ jimmy's), or dropping an engine cradle got an alternator (Monte Z34's)...I could go on and on.

I've always said that these dumba$$ engineers in an office building need to work on the vehicle systems they design...I can only immagine (or dream) of the smplistic design ideas we would see then. Not to mention the savings of flesh from knuckles.

Well, Chris is correct. The main function of the heater valve is just to control the temperature of the air entering the vehicle's interior which limit the amount of coolant that goes through the heater core. But some works with just a plastic cover for the heater core. Anyway, I got a hold of this 4-Seasons Heater Valve if you might want to have one again.

i definitely got a new one at AutoZone for less than 30 dollars. I think it was 15 there.

had to replace mine when it literally just crumbled apart one day. that was fun.



EDIT: just found the receipt: it was $13.99

Ok i am confused because i have mine in a box in my room and want to know if i should go through the trouble of putting it back on or not. my heat gets warm but not hot. would this valve have anything to do with that.

Yep put it back on if you want heat.

yeah you better put it back. Anyway cherokee, that's a lot of savings!It's even less than half the price of that of 4-Season's. When did you purchase it?

Mines the same way-it gets warm, not hot, and it takes like 20+mins. the kid before me really screwed the Jeep up, could it be possible it missing this valve or something undetectable or should i just get a new heater core...

I just finished putting on a new heater valve and hoses on my '95 XJ. The only thing this valve does is allow hot coolant to flow into the heater core. It's either on or off. Heat or A/C dash control. The HOT / COLD dash control moves the blend doors to adjust the temperature.

If you turn the question around a little bit it might be easier to answer - because I don't know :)

Is the heater control valve needed at all? If we don't have one then we connect the hoses directly to the heater core intake and outflow from the thermostat and water pump. So then we have hot coolant running to the core at all times but I would think the blend doors would block the heat from getting into the passenger compartment while set to the A/C - Cold position.

Later XJs dropped the valve altogether and went to the direct to heater core setup. How does it work for them if not flowing through the heater core at all times too?

I converted to an open system last summer I got rid of the whole hose mess.

yup
 

simply because to replace it is inexpensive, yes it would probably be best to just put a new one in...i have and if i member it was a simple in-stock store shelf peice.....fix n enjoy your xj heat while u can haha

I've been redoing my cooling this weekend (switching to open style on a 90 4.0) and I decided to bypass it. I've had issues with my heat which I cannot pinpoint and this is just another piece of the puzzle that I didn't want to worry about. My brother has ran his cherokee with no valve for a year and has had no complaints, this is the main reason I took the plunge to try it.

It shuts the coolant flow off to the HVAC box...otherwise you wouldnt have cold A/C...alot of people put the the Brass Heater shut off valves because they stop 100% of the coolant while the stock valve doesnt.