What's the purpose of the heater control valve??
 

I have a 1996 Cherokee 4.0 and the 6 month old heater valve started leaking yesterday. Sense it's winter now and everyone says these things suck no matter what brand you buy,I figured I'd just connect up all the hoses with connectors so I'd have heat for the winter. I THOUGHT this meant I wouldn't be able to use the AC but right now I'm using it with no issues at all. No raise in temperature or anything. The heat still works when I switch that on. I'm confused as to what the purpose is of this valve if I can still use both the AC and heat separately. Thanks in advance.

It's there to piss you off. Did it work?

The heater control valve controls whether to let the hot coolant from the water pump pass through the heater core in the cab. These are mainly used for allowing the engine to warm-up easier and quicker in all seasons, especially winter.

However, aftermarket ones are of horrible quality, so people just delete them. Later models (97+) don't have them from the factory due to elimination of vacuum systems, and therefore anyway to control it, and overall saving money.

Getting an OEM one from the dealer or junkyard is your best bet to replace it, if you want to replace it.

Overall, the valve is intended to help the average ding-a-ling in starting up the engine, and try and reduce the wear created by cranking the engine and immediately starting to drive. However, most companies have gotten rid of them because most people crank the heat on when they start the car. So they don't want to try and fix stupid anymore, and instead deleted it.

Its purpose is to bypass the heater core when the heat is not in use, so coolant only flows through it when needed. When my control valve exploded on my '96, I got rid of it and just ran generic heater hose straight from the tstat housing and water pump right into the core. I never bothered to fix or use my AC so the constant heat to the core was no issue. If your blend doors keep enough of the heat out for your AC to work fine, you will have no other issues. Just make sure you plug off the vacuum line that is not in use.

Yes,very much!! I was half way to work when it started smoking,so I cut it out,popped a 13 mm and a 7/16" deep socket in each hose,and went the rest of the way sweating more than the car had leaked.

Ditch it. Not needed. Use longer hoses to and from the core. Bob's your uncle.

IIRC the 97+ hoses should work.

On a '96 I used to own it would leak very slightly occasionally. In the winter only. And not every year. I attributed it to what people call the winter leaks. Think the theory is the colder weather, expansion and contraction cause the leaks. Sometimes a little tighten here and there would help but just chalked it up to one of those things. I never tried it but somebody suggested using that Indian Head Shellac. My understanding about that stuff is that once you use it those hose are never coming off. Stuff is kinda like glue.

I ditched mine as it's just a common failure point anyway. Many others have as well with no repercussions. My AC cools just fine in Virginia summers without it. The blend door seems to do the job.

The heater control valve is there to make your heater core ROT from sitting with the same stagnant coolant all summer long. :icon_eek:

After replacing the one on my 92 a few times and noticing that my 99 didn't have one, I just replaced the hoses on the 92 and deleted the valve.

Absolutely NO issues for the past 3 years. A/C is ice cold in the summer and the heat is hot in the winter now.

I think I used 5/8 and 3/4 hose on my 92.

Like Diskman mentions, I believe they are indeed different sizes. I've chosen to leave the valve in my 3 Jeeps. In hell'a hot weather I don't want any 200* water circulating in my cab, period. That said if your blend door seals are good, and you don't mind running a tad more AC, you are fine deleting the valve. My AC only works in one. I think with good AC you would never miss that valve.

Of course I turn it on even in summer now and then to run the de-frogger. The argument that being able to stop the heat flow into the cab will clog your heater core, holds no water here.

Just go to Napa and get new heater hoses for a 97 and later.

Google "collage".